Case-study: silent PC

Case-study: silent PC

Overview for creating a silent air cooled (desktop grade) system. This is NOT a buyers guide but a case-study on how to create a silent system and/or how one can reduce the noise in an existing system.

Each section has a tl;dr summary for your convenience.

tl;dr  use a case with good airflow, use silent PWM fans (as least as possible) and undervolt the GPU and/or CPU. Optimizing for sound is similar as optimizing for cooling but with turned down fans for optimal noise instead of performance.

Use-case / constraints

  • Moderate budget (no full custom solutions, consumer grade components, …)
  • Support high performing hardware, no compromises
  • Only moderate modding (if any): drilling, cutting, … is fine but NO full custom solutions, CNC, …
  • Low/no maintenance solution (thus air cooling)
  • Long term solution (works in all seasons and lasts >10 years)
  • Repairable, replacing a component must be reasonable/low effort
  • Located on a desk, close by (~60cm from ears)
  • No hard drives (flash storage only)

Goal almost inaudible system (<25 dB) under full load, with acceptable thermal performance and no thermal throttling.

Synopsis: what is sound, sources and how to reduce it

tl;dr noise is produced by air flow obstructions and especially (air vertices of) fans.

Sound is a mechanical wave of pressure and displacement (vibration) which propagates through a medium (air). It may vibrate at any frequency. The wave slowly looses energy (loudness) while traveling or bouncing off a surface. Loudness is measured in decibel (dB), a 10 dB increase is typically perceived by human hearing as double the loudness. High frequencies are often perceived as louder and more annoying e.g. a higher pitched 20 dB(A) noise might be perceived more annoying then a 30 dB(A) lower frequency noise. Humans can only hear frequencies between 20-20k Hz. Sounds (consisting of a bunch of frequencies, its frequency spectrum) where the frequencies do not differ much are less noticeable. In short: human hearing is not physically objective. Try to search for reviews which include sound samples, or the frequency spectrum, so you can judge for yourself as tables with dB(A) values do not tell the whole story.

In (consumer grade) computers there are 2 sources of sound. First electrical, coil whine, which may come from the motherboard, PSU or GPU. It is caused by (vibrating) capacitors producing a high pitched noise and may range from barely notable to unbearable. There is not much one can do about it, try to (hot) glue the noisy capacitor to neighbouring components (dampens the vibration, typically already done by the manufacturer) or replace the whole component.

Second source, air flow (for cooling the system), or more precisely turbulence by obstruction of air flow and air vertices from fan blade edges. With the (low) air speed in computer cases the fan blades will generally cause more noise then obstructions. In addition fans vibrate (slightly) and are often mounted on thin metal or plastic surfaces (case) which may amplify the vibration (inside the case, it functioning as speaker box) to become audible. Using rubber pads (often included in the case/fan), and properly tightening the fan, should resolve these vibrations. Reducing vibration sounds is also called sound deadening.
The most efficient air flow in a single direction without any obstructions (aside from heat-sinks) as they also lower the air speed,cause turbulence and/or redirect(/scatter) the air flow (undesired if the obstruction is not a shroud). Thus obstructions required fans to spin faster (louder) to achieve the same cooling result. Fresh (cold, room temperature) air should be sucked in from outside the case and hot air being (immediately) exhausted out of the case. Re-circulation within the case is undesired as cooling with hot air is less efficient then cooling with cold air (fans have to spin faster, thus more noise, for the same cooling performance). Typically the air gets heated to 40-45 °C. Simply adding more fans to a system does not always improve the air flow, and may even have a negative effect if they hinder the existing air flow. For a silent system the aim is to have “just enough” air flow for the cooling to work properly while running the fans as slow as possible.

Instead of reducing the amount of noise produced it can also be reduced by being absorbed, when it bounces off a surface (it will also travel trough) a portion is reflected and energy (dB) is lost, thus it becomes more quiet. Dampening, reduces resonance but can largely be neglected for our use-case. Decoupling by hindering the direct pathway of the sound, e.g. build a wall next to a highway, however as the air has to move freely for cooling purposes this can rarely be improved upon in a computer case. Distance the further away from a sound source the more quiet it will be (loosing energy as it travels); hence moving the computer case as far from your ears as possible. Adding mass (reduce transmission), dense material reduces sound waves from exiting a material (losing energy, thus dB, thus more quiet). Additional methods are: directed reflection, when sound is reflected it can be directed away from the observer or scattered around (diffused) so the loudness in all directions is less. However those are not applicable for our use case. Sound trap/muffler/silencer/attenuator by bouncing sound around in a (almost) closed chamber with sound absorbing material inside it loses energy (thus becomes more quiet). The effectiveness of all these additional methods depend on the used materials. Ideally a computer case would be turned into an acoustic anechoic chamber (reduces internal sound reflections) or sound trap.

Avoiding the sound being produced in the first place will always be more effective then trying to reduce it afterwards (for our use-case).

Being “inaudible” is a subjective notion as it depends on how loud a particular environment is (the noise-floor). Next to a busy highway a computer fan at full speed will be inaudible, in the middle of an open field at night it will be loud. The fan is, physically, equally loud in both settings. So depending on your specific situation it might be easier, or harder, to create an inaudible system. Indoor, rather quiet, rooms typically have a noise floor of 20-30 dB(A). Making a system (significantly) more quiet then the noise-floor is not useful/effective.

Synopsis: heat production and cooling

tl;dr the GPU produces the most heat (highest power consumption), followed by the CPU. Create a negative pressure in the case, if possible. Create a good air flow. The difference between a decent and "perfect" airflow is marginal (a few °C). The difference between a bad and decent airflow is substantial.

Electronics work by electrons (current) moving through them, they produce heat when electrons lose their energy (from the electric field) by interacting with other particles in the electronics. The higher the energy of the electric field (voltage) the more energy the electrons can loose and generally the more heat is being produced. As perfectly efficient electronics (electrons are not hindered) do not exists all electronics produce heat.
Modern computer components cannot be damaged by running too hot, before damage occurs they will reduce their power usage (thus heat production), called thermal throttling, in an attempt to lower the temperature. Worst case the system shuts down (without notice). However constantly running the system at high temperatures will put additional stress1 on the electrical components, possibly shorten their lifespan, thus (for hot silent systems longevity using) higher quality components are advised.

Air cooling works by transferring heat from a component ( chip) into a heat sink (typically metal), with a large surface area and thermal mass, which transfers the heat to the air (when the air comes in contact the heat sink by bumping into it). The more surface area the heat sink has, the more efficient heat is transferred to the air (as more air bumps into it). By creating an air flow through/over the heat sink fresh (room temperature) air is converted to “hot” air which is pushed away (to be exhausted out of the case, preferably as fast as possible to not heat other components). Even though air cooling is the most commonly used method of cooling computers, it is overall not efficient at all (but it works). The lower the room temperature and the lower the humidity2, the more effective air cooling is. Computers are thus effectively air heaters and depending on the system specifications and air volume (size) of the room it can notably affect the room temperature.
Typically the airflow direction in a computer case is: horizontal (front -> back or back -> front) or vertical (bottom -> top). A good (air flow) case will provide good positioning of the components/fans such that the air moves rather unobstructed and hot air is swiftly moved out of the case. In theory the better the air flow the slower the fans can spin (to provide the same cooling performance) and thus less noise being produced. In practice often both horizontal (CPU) and vertical (GPU) air flow is used because of how GPUs are cooled (see below).

Components

The CPU (central processing unit), under maximum utilization on non- overclocked high-end (consumer grade) systems, the CPU typically uses 80-250W. More moderate CPUs <80W. This has been more or less stable over the years with the tendency to gradually rise for the higher-end models (2022). Even for the most power hungry (consumer) CPUs this heat can be managed by (high-end aftermarket) air coolers. Typically the CPU (cooler) is positioned at the top back side of the case directly exhausting the hot air out of the case through the top and/or back side.

Source: enermax.com

Link: CPU cooler air flow

The GPU (graphical processing unit) typically uses the most power and the difference between low/mid-end (75-250W) and high-end GPUs (250-550W) is large. Newer generations have the tendency to require more and more power (2022). GPUs, as opposed to CPUs, do not support aftermarket air coolers and their cooler design is not ideal for air flow. Cold air is sucked in through the bottom by fans (image is upside down) and exhausted through the sides where typically (not depicted) most air is exhausted on a single side. The air flow is bend 90° and hot air is then exhausted in multiple directions (scattered) in the case. Even worse typically the GPU is located below the CPU, thus the hot air from the GPU could affect the air cooling capabilities of the CPU (cooled with above room temperature air). GPUs come with 1-3 fans and shroud around the fans to control where the host air is exhausted (or, unfortunately, sometimes just for esthetics). The fans are typically slim to reduce the height of the GPU making them less efficient in moving air then regular fans (thus requiring higher speeds, more noise). GPUs are generally loud when their fans are at full speed. Air flow cannot be improved, the most important factor is providing enough cold fresh air (typically through the bottom of the case).

hsrc="/posts/case-study-silent-pc/images/gpuflow.webp" hwidth="650" hheight="498" /><figcaption><p>Source: howtogeek.com</p><p>Link: <a href="https://www.howtogeek.com/365215/what%27s-the-difference-between-a-blower-and-an-open-air-gpu-cooler/" target="_blank" rel="noreferrer">GPU cooler air flow (upside down)</a></p></figcaption></figure>

The PSU (power supply unit) produces heat by converting electricity from your wall socket to the voltages required for the system, this conversion is not perfectly efficient hence heat production. The more efficient the power supply, and the less power it must deliver, the less heat will be produced (thus easier to cool, thus lower noise).
They cool themselves by a fan sucking in cold air and exhausting hot air at the back, typically directly outside the case.

hsrc="/posts/case-study-silent-pc/images/psu.jpg" hwidth="500" hheight="457" /><figcaption><p>Source: build-gaming-computers.com</p><p>Link: <a href="https://www.build-gaming-computers.com/how-to-install-power-supply.html" target="_blank" rel="noreferrer">PSU air flow</a></p></figcaption></figure>

Other components typically do not require dedicated cooling, their heat sinks (if any) are cooled enough by the general air flow in the case.

Airflow considerations

Hot air has a tendency to rise, called convection, creating a (very faint) airflow (circulation). Even though this effect can be overcome by the faintest air flow it could create hot pockets of air at the top of the case (or cavities), heating the case. This is to be avoided if possible but typically does not significantly impact cooling performance. Often cases have top mesh panels for this purpose. Vertical air flow will therefore always be bottom -> top.

If not enough fresh air is available for a fan it is choked, this typically happens in cases with fans mounted behind a closed front panel (with not enough ventilation holes). This severely affects the performance of the fan, requiring them to run at a much higher speed and might cause additional noise by the air moving at high speed through the ventilation holes/mesh. Choking is very visible in case reviews which include a thermal and noise tests. Must be avoided.

Dust accumulated on heat sinks or fans reduce their efficiency. Except if you have a filtered HVAC system there will be dust in the air of your room. Air cooling circulates air through your computer case, which is slowed down by obstructions (heat-sink, cables, …), the dust in the air get stuck on these obstructions or becomes too heavy (for the slowed down air flow) to still be carried by the air and accumulates in the case over time. Raising, or moving, your system off the floor reduces dust accumulation (as there is typically more dust on the floor then airborne). Most moderns cases come with dust filters which help a lot (if cleaned once in a while), as general rule of thumb all air entering the case should go through a dust filter. However periodic removing dust (yearly) is unavoidable to keep a system in good shape. Dust filters for computers are designed for high airflow and certainly do not catch all dust (as opposed to HVAC dust filters).
There are 3 ways to manage air pressure inside in a case: negative, evenly and positively pressured. In positively pressured set-ups more air is pushed into the case then out of the case, e.g. 2 fans are pushing air into the case and 0 or 1 fan is pushing air out of the case. The results in air trying to escape the case through ventilation holes or anywhere the case is not air tight. Evenly pressured is where the amount of air sucked in is roughly the same as the air pushed out, for example 1 fan pushing air in and 1 fan sucking air out of the case. Finally negatively pressured set-ups have more being air pushed out of the case then into the case, e.g. 2 fans push air out and 0 or 1 fan suck air in.
Negative air flow accumulate the least dust, especially if there are 0 intake fans. The air flowing into the case has a lower speed, and thus lower capacity to carry large dust particles. Also the faster air is pushed into the system (by intake fans) the less likely it is to stick to dust filters. Not all cases are fit for negative air pressure as the case must be closed enough so enough (negative) pressure may build up inside. If there are large mesh/ventilation panels you might not be able to create the desired air flow as the air will primarily be sucked in through the easiest (shortest) way it can find.
Neither pressure set-up provides significant better cooling nor noise performance.

How important is air flow for a silent system? Moderately, bad airflow or choked fans will have a significant effect on the cooling performance (thus noise) however the difference between a decent and “perfect” airflow is less important. Case reviews demonstrate this, as the difference between the best and middle of the pack case is typically <5 °C. Noise impact is a bit more variable as the quality of the included fans varies (which can be replaced) a lot and/or there are more airflow obstructions (which sometimes can be removed). It is important however that the airflow works well for all components (CPU, GPU & PSU).

Out of the box solutions

tl;dr expensive and does not meet all requirements.

An out of the box solution exists, which ticks all the boxes except budget: the Apple’s Mac Studio. It only produces max 25 dB (albeit people report it being audible, and some find the frequencies annoying), is very small and very high performance (if you buy the higher-end models). However being way out of budget, and tied to Apple’s ecosystem, this is not a real option. That said its performance/noise (considering the size) is impressive and hard to replicate with off the shelve components.

Other out of the box solutions typically suffer from the same issue and/or do not tick all the boxes.

Passive systems

tl;dr not enough cooling capacity for dedicated GPUs (nor high-end CPUs). This option is thus not further explored.

Passive systems have no fans, semi-passive systems have 1 or 2 low speed (exhaust) fans which typically only turn on when the system in under heavy load. These are hands down the most silent (and maintenance free) systems one can get. They rely on natural air convection and high cooling capacity of the case to transfer their heat to the air. The effectiveness of passive cooling is heavily correlated with the room temperature3 (lower is better4).

Except for the most low-end GPUs (usually not significantly better then CPUs with integrated GPU) too much heat is produced to be cooled passively. High-end CPUs on the other hand require semi-passive solutions but are otherwise feasible. Mid-range CPUs, or below, can be completely passively cooled if not constantly under maximum load.

Specialized cases (with higher thermal capacity, i.e. the whole case acts as a heat sink increasing the contact area with the air around the case) are expensive (>200 euro), typically have limited hardware compatibility and thermal throttles high-end systems never the less. Availability/choice is typically also very limited.

Ordinary cases can be used as well, excellent support for natural convection5 and having a large air volume (i.e. bigger cases) are a must. The case is the most important factor for these systems. High CPU temperatures are inevitable, for >80W CPUs. ATX motherboards are highly preferred6 for systems with a GPU. NVME drives, if any, must have a heat sink.
There are specialized passive CPU coolers, e.g. Noctua NH-P1, which can be used semi-passively as well. Noctua also provides an incomplete list of good cases for passively cooled systems.

Passive PSUs are available albeit more expensive, hard to find and should have a dedicated area in the case as hot air from the CPU and GPU will reduce their cooling capacity. Serious over-provisioning (>2x) is highly recommended (see the PSU section).

Impact of part selection on system loudness

tl;dr the parts determine the loudness, thus are key. The noise can typically not be meaningfully mitigated afterwards. The lower the power usage, the easier to cool.

This section only discusses components affecting the loudness. As general rule of thumb the less power a system uses, the easier to cool and the more quiet it can be.

Fans

tl;dr fan selection is very important to reduce the noise. Use PWM fans. Bigger is better.

There are two type of fans, PWM ( pulse width modulation, 4 pins) and DC (direct current, 3 pins). PWM fans are turned on and off very quickly (in a duty cycle), the longer they are turned on the faster they spin. This is typically managed by the motherboard. They last longer and are more energy efficient then DC fans (which are always on).

Fans are usually optimized for either static pressure (in mm H₂O) or air flow (in m³/h). Airflow indicates how much air a fan can move while static pressure outlines the pressure(/speed) of the air being moved. Static pressure fans are typically used on heat sinks as they can force the air through the heat sink/radiator. Bigger fans tend to have lower static pressure (especially when normalized for noise). For optimal performance the difference matters (a bit) but both fan types can do the any job as long as they move air.

Fan size matters for air flow, the larger the fan the more air it can move at low speeds (thus lower noise). The standard size is 120mm, anything below is generally not worth the noise they produce (if you have the choice). To put it in numbers: a 140mm Noctua NF-A14 PWM pushes 140,2 m³/h at 24,6 dB(A) while the 120mm Noctua NF-A12x25 PWM pushes 102,1 m³/h at 22,6 dB(A). The 180mm Dynamic X2 GP-18 PWM pushes 76.33 - 261.29 m³/h at 16 - 35.4 dB(A). Thicker fans move more air then slimmer fan (at the same speed), and thus are preferred.

In general less fans is better to reduce the noise, however two fans at low speed will be more quiet then a single fan at moderate or high speed. Adding fans will drive up the cost, and might not be an option depending on your case (size) though.

Check reviews to find the currently most silent fan for your budget. Be aware that the performance at lower fan speed is much more important then the maximum as the fans should be running as slow as possible to reduce noise; your conclusion/need might be different from the reviewer! You want the highest air flow/static pressure in the 15-20 dB(A) noise range.

Anything below 20 dB is good. Below 15 dB is great.

Fans ( bearings) tend to get louder as they wear out over their lifespan, depending on the quality this can happen sooner or later and be neglectable or unacceptable. Some fans types (sleeve bearings) will wear out faster if placed horizontally depending on which type of bearings is used.

Take the manufacturers dB specifications between manufactures with a grain of salt as typically the set-up (how it is measured) is not specified, thus comparing apples and oranges. Check reviews with an identical set-up.

If you are planning to only spin up the fans when required pay special attention whether the fan supports this. Most fans (2022) do NOT turn off on their lowest (PWM) setting.

High quality fans can be surprisingly expensive.

CPU Cooler

tl;dr use the biggest silent cooler that fits your case. Rather important for a silent system.

In general the biggest cooler which fits your case will cool the best. Multiple fans on the CPU cooler typically only help out 1-3 °C and thus are not worth the additional turbulence/noise. Buying a multi fan CPU cooler and simply not attaching the second (or even third) fan is also an option.

Check review to find the currently most silent CPU cooler for your budget. Be aware that the performance at lower fan speed is much more important then the maximum as the fans should be running as slow as possible to reduce noise; your conclusion/need might be different from the reviewer! You want the best performance in the 15-20 dB(A) noise range, unfortunately most reviews only start from 30 dB.

Anything below 25 dB is good, below 20 dB is great.

Take the manufacturers dB specifications between manufactures with a grain of salt as typically the set-up (how it is measured) is not specified, thus comparing apples and oranges. Check reviews with an identical set-up.

It is not important to get the absolute best CPU cooler, good is sufficient. If your CPU does not produce a lot of heat (<80W) smaller, cheaper, coolers are fine.

GPU

tl;dr consult reviews and pick a silent GPU. Very important for a silent system, often the loudest component when under full load.

As nothing can be changed about the GPU coolers (after market air coolers are generally not a available) picking a silent model (good heat-sink) is important. There are quite some variations in cooler designs and their noise performance. Check reviews. Typically the bigger the heat-sink the better the cooling capabilities and the better suitable for de-shrouding, unfortunately these models are sometimes overpriced. Make sure the GPU turns off its fans under low utilization.
Another strategy, which will yield the same outcome, search for a GPU with lower power consumption (and has decent cooling). See also undervolting which lowers the power consumption.

Avoid blower style coolers as they are louder for consumer grade components however they are less dependent on the air flow in the case. Fortunately modern GPUs do not use these designs anymore.

GPU fans tend to be slimmer, and thus less performant then regular fans and tend to wear down faster as well (depending on the quality). Older second hand GPUs will typically be louder then originally bought/reviewed. Fan replacements sometimes exists (and are typically easy to perform) otherwise deshrouding might also be an option.

Take the manufacturers dB specifications between manufactures with a grain of salt as typically the set-up (how it is measured) is not specified, thus comparing apples and oranges. Check reviews with an identical set-up.

Under full load the GPU tends to be the loudest component in the system.

Do not blindly trust power read-outs from the GPU (software), as usual you have to read the fine print to find out what is actually measured. At the time of writing (2022) AMD under reports and NVidia does a good job.

The efficiency of voltage converters, on the GPU, scale with their temperature. The higher their temperature the less efficient, thus more heat production and ultimately more noise. Some cooler designs do a better job at cooling these then others which should be reflected in a lower overall power usage. The effect is measurable but neglectable.

Motherboard

tl;dr avoid motherboards with a fan.

Although rather rare, some motherboards come with a small fan attached. These tend to be of poor quality and become (or are) loud over time. Avoid these.

Flash storage

tl;dr not important.

NVME storage uses more power then SSDs, thus will produce more heat and requires a heat-sink. However compared to the CPU and GPU the produced heat is neglectable and should not affect the total heat output of your system (meaningfully).

PSU

tl;dr ATX/SFX-L PSUs typically do not produce significant noise, SFX PSUs on the other hand could be the loudest component in your system (at idle). Check reviews/labels. Some overprovisining is advised. Use a semi-passive PSU. 80 Plus Gold, or above, is fine.

ATX PSUs (various L x 150W x 86H mm) and SFX-L (125L x 125W x 63H mm) have a 120mm fan, SFX (100L x 125W x 63H mm) a 92mm fan. ATX and SFX-L typically are quiet. SFX often require higher tier models (with the best efficiency ratings) to be quiet. SFX and SFX-L are notably more expensive then ATX, there is a more limited choice and typically only come in higher-end product lines with better efficiency. Even more niche is TFX, Thin Form Factor Power Supply, with (175L x 85W x 65H mm) which only exists in low wattage. Choice is very very limited. Flex ATX PSUs (sometimes called 1U PSUs) are aimed at servers (no nonsense), (150-220L x 81.5W x 40.5H mm), come with a 40mm fan, are typically rather loud at full load (high density of components and small fan), and are efficient (gold/platinum); cost (new) is comparable to SFX or higher. Besides form factor there are no differences/benefits between the different types. Pick a PSU with semi-passive mode where the fan only spins up when required (typically >30% utilization). Passive PSUs exists but are expensive, rare, and often rely on some air flow being present; generally not worth it.

Consumer PSUs use the “ 80 Plus7 label where gold or above is good. The difference between gold and titanium (best) is ~5%, at a significantly higher cost (2022).

One trick to make the PSU more quiet is to over-provision, especially for SFX, where the PSU can handle more then the system will ever require. This reduces the stress on the PSU as PSUs become less efficient close to their maximum capacity. Usually self build systems are already naturally over-provisioned as it is hard to calculate the exact required power for a system and most people prefer to be rather safe then sorry. If you go overboard (>1.5x expected power usage) it will drive up the cost considerably and is only worth it if you have the budget, (<30% utilization will make a semi-passive PSU passive) or for passive systems.

PSUs always have a fan guard/grill, which may cause additional noise for no benefit, thus should be removed (voids warranty). Sometimes it can simply be screwed off, otherwise you will have to cut it out.
The fan can be replaced with a silent (after market) fan (voids warranty), albeit is usually not required. PSUs use static pressure fans.

Check the Cybernetics database, or reviews, and pick the most silent PSU that fits your budget. If you are unsure how much power (W) your system needs use an online calculator.

As of 2022 a new specification for power supplies is announced, ATX 3.08 which comes with Cybernetics certifications instead of 80 Plus. Besides efficiency it also comes with a noise label (and fully detailed report). It is the first big specification change in +10 years but no products are released yet (at the time of writing). It might be worth while to hold off on buying a new PSU to see if the new specification will be widely adopted as it has a different connector for the GPU. Some of the current PSUs are already rated with the new (noise) rating, which might be of help when picking a new PSU.

When using a SFX PSU selection is important to create a silent system, for SFX-L and ATX form factors less so (GPU will be louder).

Case

tl;dr important but also subjective due to esthetic preferences. A good case must: facilitate a good air flow with little, or no, obstructions. Check reviews. A good case does not have to be expensive at all.

A case does not change how much heat the system generates, that entirely depends on the hardware and system load. Larger heat-sinks and more airflow (facilitated by the case) will make the system run at a lower temperature, but will not affect the total heat output. Facilitating a good cooling solution, and holding the components, is the only job of a case. The case which requires the least air flow to keep the system cool (to neither thermal throttle nor affect the life span) can in theory be made the most quiet. The exact required air flow strength for a system can be calculated albeit is typically not provided for consumer grade components.

The case also determines the looks of the system, which is subjective. Check reviews of cases you like and pay attention to the noise and temperatures. Silent cases do not have to be expensive at all! Generally one pays more for looks then for function.

Case size is more a personal preference, except for the smallest (SFF) cases all case sizes are fit for building a quiet system. Available case form factors: full tower (biggest), medium tower or mini tower. Small form factor (SFF, <20L9 only ITX motherboards) and medium form factor (MFF, 20-40L, supports (ITX and) mATX motherboards) terminology is also used. Case size determines which components can fit which affects the cost. Motherboards come in: ATX (30.5 L x 24.5 W cm, >4 PCIe slots), mATX (24.4x24.4 cm, up to 3 PCI slots) and ITX (17x17 cm, 1 PCI slot). PSUs come in: ATX (various L x 150W x 86H mm), SFX-L (125L x 125W x 63H mm) or SFX (100L x 125W x 63H mm). For both the smallest options are the most expensive, up to 20-50% difference for the same performance. That said generally the bigger the case the more expensive, premium SFF cases being the exception (and most expensive).
The larger the case the more fans will fit, although this might not always help with airflow it does allow fans to spin at a lower speed (thus reduce noise). On the other hand there is more chance of internal air re-circulation and hot air pockets. Smaller cases are more effective at exhausting hot air quickly, however smaller SFF cases lack room for good (unobstructed) air flow.

Cases have wildly different cooling performance, some designs completely neglect cooling (usually in favor of esthetics). Pick a case you like and check reviews.

MAtx form factor is more popular in Asia then in Europe (at the time of writing), do not be afraid of brands lesser known in the West (e.g. Jonsbo). Quality is often on par or even better.

If one does not mind a bit of tweaking (cutting, drilling, …) many cases can be improved with rather minor changes (see other sections below).

Custom cases, build to specification with designs to reduce the produced sound as far as possible, are out of scope and thus were not considered however can achieve incredible results.

SFF cases require the most attention with respect to component compatibility, cable management and available air flow options.

Case selection considerations

  • Cases made with thinner panels, even with sound damping materials, are more noisy then thicker panels.
  • Special sound dampening cases (usually reducing the noise a few dB while lowering the pitch) are generally not worth it as they typically constrict airflow too much requiring higher fan speeds neglecting the sound dampening effect(s). However there are exceptions.
  • Make sure the PSU is mounted with anti-vibration pads. Ideally everywhere the PSU touches the case there should be an anti-vibration pad. You can create your own (from rubber) if they are not included.
  • Cables are a source of obstruction for air flow, ensure cables can be properly managed (hidden, out of the air flow path) in the case. Most cases have room behind the motherboard to route cables. In SFF cases this might pose a challenge.
  • (tempered) Glass panels add ~1-2 dB, thus metal panels are preferred. Metal panels, especially aluminium, typically also provide very minor cooling performance improvements as they also act as heat sink if the system runs hot. Using plexiglass instead of tempered glass adds even more noise (but is rarely used in modern cases). Steel panels are the best.
  • Included case fans are typically not the most quiet (especially for cheaper cases) and quality may very a lot, check reviews!
    • This makes case reviews tricky as replacing fans in a louder case might in the end perform better then a more quiet case with good fans.
  • Ensure all intakes (with or without fan) have a dust filter. Nylon dust filters are the most quiet (they are cheap and can also be bought afterwards to replace the originals if you are a bit handy). The effect is typically neglectable however, especially at low airflow speeds.
    • Dust build-up in the case reduced air cooling efficiency

Case airflow considerations

  • Ideally air flow should move in a straight line without any obstructions
    • If you have a horizontal intake and outtake fan which are not level the air will have to move up/down, this will cause additional turbulence (thus more noise and reduce the air speed/flow)
  • The higher the (static) pressure inside the case (positive or negative) the less it helps to add another fan (as it must fight the pressure first to move air in/out)
  • Fans may not be choked
  • Using bigger fans (140 vs 1200 mm, if the cases design allows it) helps to reduce noise
  • Make sure intake and exhaust fans are COMPLETELY unobstructed for best results. Designs that have fans with a solid panel in front of them are usually a no go. Mesh is also not ideal but typically unavoidable.
    • However, the lower air the speed, the less noise is being generated by obstructions; thus the less it matters
  • Dust filters on exhaust fans may increase the noise (and/or impede air flow) and have no benefit, ensure they can be removed
  • The GPU should be able to suck in (or being provided with) enough cold air from outside of the case (directly, typically from the bottom, or through air flow from an intake fan)
  • Vertical GPU mounts typically have poorer performance except when the GPU intake fans are directly placed next to a ventilated panel to suck in fresh air from outside the case (so no glass panel).
  • Make sure your preferred CPU cooler fits, especially in SFF cases the available hight varies
  • Adding fans under a horizontally mounted GPU (with almost no space between the fan and the GPU fan) usually hurt more then they help as the fans are “fighting each other for air”. At least a few cm between the fans is required.
  • If the GPU is located at the bottom of the case (directly or a few cm from the bottom panel), sucking in fresh air from underneath the case, ensure the feet of the case are high enough so that enough air volume is available to be sucked in. Too little space (small feet) and the GPU will be choked. Typically feet can be swapped rather easily afterwards. Often a point of attention for small SFF cases.
  • Mesh panels may hurt the airflow, if there is a large area with mesh which has no fans attached it will be hard to create any static pressure inside the case to create an air flow. Mesh panels may also cause undesired air flow (e.g. air intake next to exhaust) as the air will take the path of least resistance.
  • Ensure the air flow does not suck previously exhausted (hot) air back into the case (as “fresh” air). E.g. if the PSU is at the bottom and exhaust hot air at the back anything that will suck in cold air from the back will suck (at least a part) of the hot air from the PSU back into the case. This will affect the cooling performance.

Fan grills (and mesh)

tl;dr impedes air flow and increases noise (usually minor) without any benefit, remove if reasonable.

The main purpose of fan grills is to save your fingers from accidents. Which might be a real life saver when having pets or children around. In small cases they may also prevent cables from touching the fan blades. That said if attached to a fan they obstruct the air flow and on top cause additional noise. It ranges from <1 dB to >15 dB, which is enormous! The best fan grill is the simple round wire (swirl), see picture below. Mesh panels introduce less noise (results depend on the hole size) BUT they do change (increase) the pitch of the sound making it more annoying, and noticeable.

Lowest noise fan grill

Most cases do not have removable fan grills, so they have to be cut out of the case. Before cutting make sure the fan grills are not required for the structural integrity of the case, usually it is not.

Mesh panels typically cannot be removed by design and are part of the case esthetics. Not all cases have mesh panels though, or no significant air flow goes through the mesh panel. A mesh panel a few cm above or below a fan will already cause notably more noise; again also depending on the hole size. The higher the air flow the worse the effect becomes, low (and natural) air flow is ok (inaudible).

How much a fan grill obstructs the air flow heavily depends on the design, it ranges from neglectable to noticeable.

Small form factor cases

tl;dr the larger SFF cases can work but are a mixed bag for air flow. Decent, not great, results can be achieved. SFF systems will run hotter then bigger cases.

The larger SFF cases are good candidates (>12L, preferably >18L) and almost all have the same internal design as there are only some many options to efficiently cramp components into a small space. One case is just that 1 (or few) cm smaller or wider then the other. Most only support SFX(-L) sized PSUs which are more expensive. As an ideal airflow is practically impossible , due to the limited space (the air has to make turns), they typically rely on mesh panels to directly suck in air from outside the case. Most designs support top fans to exhaust the hot air (aiding natural convection). Therefor you often see the cases packed full of (very low speed) fans. That said performance is not bad. In SFF the fans are often more important then the case for a quiet system. Cable management is a challenge and, depending on (the size of) your case, is impossible to get perfect. SFF cases rarely have a front fan.
SFF cases require more care when selecting components to ensure everything is compatible as the margins and available room is more restricted (there is often a bit of a fetish to make cases as small as possible). Check existing builds and reviews to ensure the selected parts fit, and double check the dimensions for everything (provided by the manufacturer).

Specialty SFF cases tend to be more premium and go out of stock sooner then regular cases due to lower production volumes. There are exceptions.

SFF cases typically have a lot of ventilated panels making building up notable air pressure inside the case impossible. A good alternative is to only have intake fans leading the fresh air directly to the cooler using shrouds/ducts.

The smaller cases (<12L) typically have a “sandwich” layout which severely restricts the CPU air cooler height and is therfor typically used with water cooling. Not advised for silent (air cooled) builds. That said they have the benefit of decoupling the CPU from the GPU so their temperatures (exhausted hot air) do not influence each other.

Source: smallformfactor.net

Link: Dancase A4

One of the currently most popular options (for bigger SFF cases) is the Cooler Master MasterBox NR200 (376 x 185 x 292 mm, L x W x H, 18L). There are various good air cooling set-ups possible, and given it is a very popular case almost all options have been tested already.
With custom feet (possibly 3D printed) and 90° connectors the case can also be put vertical if you prefer so. Prefer horizontal/flat instead? That is possible too.

Source: lys1030

Link: Nr200

Medium form factor cases (and above)

tl;dr pick one you like with good airflow. Check reviews.

One of the smallest and most versatile MFF cases is the SAMA IM01 (391 x 185 x 303mm, L x W x H, 22L) or the one of the many re-branded models: iTek Evoke, Inter-Tech IM-1 Pocket, Tecware Fusion, CST350 PLUS, SKTC S200 and the list goes on… they are all the same sometimes with a different front panel. While being only marginally larger then SFF it does fit an ATX (or SFX,-L) PSU and mATX (or ITX) motherboard! Supports up to 4 slot GPU’s (!) and allows for big CPU air coolers. You will not find a smaller case with all these features. Air flow and cooling wise it behaves like the larger SFF cases. Note: the default fans are mediocre at best.

Source: nguyencongpc.vn

Link: SAMA IM01

One of the biggest ITX cases is the Fractal Torrent Nano (417 x 222 x 374 mm, L x W x H, 35L) only supporting ITX, 3 slot GPU, ATX PSU. It is almost twice the volume of the SFF Cooler Master NR200 (bit wider, bit longer and ~8 cm higher) with the only difference being it supports an ATX PSU. What do you gain? Close to theoretical optimal airflow by a 180mm10 front intake fan (or 2x 140 mm) and zero obstructions due to excellent cable management options. It fits the largest CPU air coolers11. The Noctua NH-P1 passive CPU cooler fits but its performance is worse then a regular tower cooler with fan on low speed. The case feet are high enough to ensure the GPU has enough frech cold air intake12 at the bottom.
It must be emphasized though almost all cases of this volume support mATX motherboards or possibly even ATX (rare) and some have similar air flow lay-outs.
So is this the best silent (ITX) case? It does perform excellent but is only insignificantly better (temperature and noise wise) then the Cooler Master NR200. Although some people report the difference is large in real life [citation needed].

Source: 新浪众测

Link: Fractal Torrent Nano

When looking at larger cases (mid or full towers) they tend to support bigger motherboards and support more fan configuration in addition to more space for air flow. Some brands specifically mark particular products as “flow” to indicate the case design emphasis air flow. In reviews these cases do indeed tend to perform better (usually) and are easier to make quiet (there is also more room for modifications, like sound absorption).

Roughly decide on the case size you prefer, pick some cases you aesthetically like that ticks all the boxes (within your budget) and check reviews.

Case location

tl;dr not in direct sunlight.

Independent of the case its location may also affect the cooling performance, even for the best airflow case. The biggest no-go is putting the case in direct sunlight as it will heat up significantly. Try touching a car that has been in the sun for hours. Depending where you live pay extra attention to plastic cases as sunlight can meld plastic and will cause discoloration (or photodegradation) over time, especially for white.

Placing the case in natural airflow, from an open door/window may also reduce temperatures.

Putting the case inside a closet (or making the closet/drawer the case) is feasible, and does help to reduce noise (especially in combination with noise dampening foam, see noise absorption). However ensure enough fresh air can be sucked in and the hot air is not recirculated inside the closet/drawer but exhausted.

Additional measures to reduce noise

tl;dr additional measures to reduce noise in an existing system. Some provide significant improvements.

Hint: if you do not have a sound meter and want more objective measures there are several mobile apps which can measure sound. As we only care about relative accuracy (accuracy between measurements) they are accurate enough for our use-case.

Undervolting

tl;dr significantly helps to reduce the produced heat but results depend on your particular components. Required in some SFF cases, especially for the GPU. Voids warranty.

Undervolting is a practice of running the CPU/ GPU at a lower voltage then the original specification. An undervolted component uses less power and thus produces less heat. This is possible due to generous tolerances of manufactures on specifications as it is very hard to mass produce chips (CPU/GPU) with identical specifications. Undervolting plays with these margins in an attempt to lower the power consumption without losing performance. The ability to do this varies by manufacturer, product line and specific chip (CPU/GPU) you bought. Using 2 identical components of the same brand will yield different results.
Below a certain limit, the CPU/GPU will not function correctly, although undervolting too far does not typically lead to permanent hardware damage (unlike overvolting).

Search for a guide, typically the same steps have to be followed as for overclocking.

Finding an exceptionally good CPU/GPU to overclock is often called winning the “silicone lottery”, the same applies to undervolting.

Underclocking

tl;dr not advised, buy lower end (less energy consuming) components instead (cheaper). Voids warranty.

Underclocking is a step further then undervolting where the CPU/GPU is made to run at a lower frequency (typically allowing for an even lower voltage) to reduce the produced heat. It is the exact same process as overclocking but in the reverse direction. However there is practically no risk when underclocking. Like undervolting results very much depends on your particular components.

Will affect the performance negatively and generally buying lower end alternatives (if available), which consume less energy, will lead to the same result and is cheaper. However if you already have the component it might be worthwhile if the performance is not required.

Search for a guide, typically the same steps have to be followed as for overclocking.

Sound absorbing/dampening

tl;dr moderately effective, only for higher frequencies (making the sound more pleasant) but mind expectations. SFF cases might not have enough space.

Sound waves reflect of surfaces, some get transmitted through the material, some get absorbed within the material and a percentage gets reflected. The goal is to absorb the sound, usually by foam. Typically a certain thickness of the material is required for it to work properly (2.5-12 cm, or more, for foam). Acoustic foam typically has specific 3D shapes (wedges and pyramids) which help absorption but these are not effective in thin sheets (used for computers) and would impede air flow.

Sound absorption and sound insulation/proofing (reduce sound transmission) should not be confused, for a PC case one wants sound absorption as the case will have holes for ventilation through which sound will be able to escape undoing the effect of sound insulation/proofing. However sound proofing is easier as thin materials typically already perform well, trapping sound inside the case will lower the noise output (sounds keeps bumping around inside the case) but results very much depends on the case (and how many holes it has). Unfortunately the terms are often used incorrectly in product descriptions.

The limited available thickness (3-10 mm) is the biggest limitation in (SFF and MFF) cases. Larger cases are at the advantage here. Such thin material will only be effective for high frequencies. It is typically applied on big surfaces in the case where sound reflects off (side front, back, top or bottom panels which do not have air flow holes). It will never be as good as reducing the source of the sound, expect 0.5-3 dB(A) improvements only significantly dampening high frequencies. Typically sound absorbing material also somewhat thermally isolates, and if heavily applied could have a measurable affect. Some foam types, open cell (generally better at absorbing), will also catch dust over time (and thus are to be avoided).

As any material will absorb sound to some degree there are A LOT of choices out there, typically made of foam. Not all materials are available as thin sheets but almost all are easy to shape and work with (and can be attached with double sided tape/glue). Materials are rated by Noise Reduction Coefficient (NRC) which is the average absorption vs reflection rate of sound when bouncing of the material. The NCR is dependent on the thickness of the material and because it’s an average, two material with the same NRC may work well at different frequencies. Typically the NCR per frequency is provided though.
Price can range quite a bit but is generally very affordable. While quality of the material matters, it does will not materially matter for our use case (thin sheets), thus the cheapest one can find is sufficient. Look for a material with the best NRC for you budget. Higher value is better (1.0 is best, full absorption). Go as thick as your computer case allows.

Some good materials: felt, Melamine foam, polyester fibre, Rhino acoustic absorption foam, Acoustic cotton, Sorbothane, Open cell/Acoustic foam, EPDM (with textile), EVA foam (with hydrogen), Polyurethane acoustic foam (PUR)

Make sure whatever material you pick is fire proof and rated for at least 100 °C if close to or in contact with the GPU or CPU cooler, almost all materials meet these requirements. If applicable the materials should also treated with anti mold. Some may slightly degrade performance over time.

Air flow considerations, the more flat the surface of the material is the less resistance there will be when air flows by (thus the better the air flow will be).

Avoid products specifically marketed towards “gamers”/computes as they tend to be overpriced. Sound absorbing/dampening is also used for cars, home theaters/studios, offices, …

Improve air flow (vents, ducts, shrouds, …)

tl;dr very significant but results heavily depend on the used components/case. Even some low hanging fruit modifications may have significant effects. Improves cooling performance.

Guiding the air flow to/from coolers or fans can notably improve cooling performance and low hanging improvements are often very easy to do. For example adding a 5 mm foam gasket between a side panel and a CPU cooler can reduce the temperature as much as 5 °C for 5 minutes of work. Finding a CPU cooler that cools 5 °C better, at the same noise level, might be impossible or cost significantly more and thus this simple mod yields very good results. This works because with the gasket all air must flow over the heat-sink of the cooler, without some air escapes though the sides between cooler and side panel (lowering the static pressure) and thus less air moved over the cooler.
The goal is to improve the cooling performance so the fan speed can be lowered for equal performance resulting in a more quiet system.

It is often the sum of a few modifications that will result in significant improvements. It is completely up to you on how far you want to go. Buying different components attempting to replicate the results (more efficient, better coolers, …) might sometimes be impossible and will certainly cost more. It could also overcomes some airflow case design issues making a mediocre case a well performing case.

Source: b3rdm4n

Link: NR200 with various air duct modifications (CPU cooler, bottom fans, feet, …)

Small and large cases both have advantages for specific modifications, for small cases air can typically be directly guide to/from a cooler while in large cases the airflow inside the case can be guided.

For consumer grade components the effect is often underestimated. However out of the box solutions often do not exists as the hardware components differ too much for a “one fits all” solution; making it not commercially viable.

Commercial grade, air cooled, systems (servers, HPC, …) all use ducts/vents to guide the airflow for maximum efficiency.

Possible improvements

Properly configuring the fans to either suck in cold air or exhaust hot air is typically the first step and provides a baseline. If you are unsure what the best configuration is consult guides, negative pressure is preferred.

  • Move hot exhaust air directly out of the case, example. There should be no way for hot air to escape inside the case. The same applies for cold air intake for the GPU or CPU cooler.
  • Avoid hot air re-circulation. This can happen in multiple ways, for example the CPU cooler sucking in hot (exhaust) air from the GPU. A PSU exhausting hot air out of the case being sucked back in but a fan above; same for the CPU cooler exhaust (if any).
  • Separating components in different compartments so their hot air does not mix.
  • Taping off ventilation holes if they create unwanted air flows or reduces static pressure of air flow (too much). The reverse also applies, creating additional ventilation holes can also help for choked systems.
  • Guiding the airflow inside the case, for example get all the cold (intake) air from the front panel to the CPU cooler area. Without the airflow being guided the air will move somewhat randomly inside the case instead of being concentrated (thus the air speed is lowered requiring the fans to speed up to deliver the same cooling performance).
  • Reduce air volume, be reducing the volume of “dead space” (space that does not contribute to the air flow or housing components) the static pressure will increase improving the air flow. This can be easily done with foam (e.g. EVA foam, which is cheap, easy to work with and shape).
  • Eliminate hot pockets of air (e.g. at the top of the case due to natural convection) which cannot escape and are not moved out by air flow. Fill it up with foam so the air is forced to be in the air flow and thus exhausted out of the case.
  • Eliminate airflow obstructions, if any.
  • Smooth surfaces causes less drag and thus slows down the airflow less then, lets say, a bunch of cables. Consider to creating smooth shrouds to cover up those areas.
  • Ensure still some air moves over the motherboard as it requires cooling, even though very little.

Experimentation will be required, as to what works best for your system. It is advised to first try things out with foam/ cardboard/tape/… anything available to you and is easy to work with before possibly creating the final modification. Practically anything can be used but foam and 3D printing are popular options. Very small changes can have significant, and unexpected, results.

Validating

As results are unpredictable and sometimes unintuitive visualizing the airflow makes it significantly easier. Use smoke (not affecting electronics), smoke machines are rather cheap and often can be rented. Depending on the output of the smoke machine smoke can first be “collected” in a big cardboard box or bottle which is then emptied around the computer. For the best results the smoke is guided directly to the intake fans through a duct or (cut) cardboard box. If your case does no have a transparent side panel remove your side panel and use cellophane to create an air tight, ad-hoc, side panel. The smoke will visualize the air flow within the case which helps to identify problems or see the effect of your modifications. Good case reviews will include this as well.

As the system is typically configured for maximum airflow under load, use Prime95 to stress the CPU and Geeks3D FurMark for the GPU. A stress test will also show the effect of modifications on the cooling performance (which is what matters in the end).

CPU modifications

tl;dr most of these techniques are more advanced but significantly improve cooling capacity.

TIM (thermal paste/pad)

tl;dr as long as it is applied correctly does not matter significantly what you use.

TIM, Thermal Interface Material, functions as interface between the cooler and integrated heat spreader (IHS). Applies to both GPU and CPU but usually the GPU cooler is already mounted thus in practice mostly for the CPU (you will have to apply it). TIM is required because neither the IHS nor cooler surface are perfectly flat (micrometer deficiencies), hence there are small pockets of air which affect heat transfer and thus performance. How severe this effect is depends on your type of, and particular, components but is always very significant. Using TIM is a must. Most, if not all, after market coolers come with decent a TIM solution (usually thermal paste).

Source: thermtest.com

Link: TIM function

Ironically the TIM itself actually negatively impacts heat transfer compared to having 2 perfectly flat surfaces in direct contact. However even with Polishing TIM is still used (albeit less), as perfectly flat surfaces are impossible to get for consumer grade components (and not cost effective at all).

Thermal paste/compound

Superior over thermal pads as they are more efficient at filling up the (microscopic) air-gaps. However only expect a few °C improvements (compared to high quality pads). The difference between thermal paste brands is typically 0-5 °C, although most perform the same. Generally getting a better CPU cooler is more cost effective then buying new thermal paste. However for the absolute best result, get the best thermal paste.

How thermal paste is applied also impacts the performance, as too little will not cover the whole IHS and too much will simply make a mess. There are heaps of guides how to best apply it, the conclusion is always: it does not matter as long as you apply enough.

Thermal paste degrades (separates) over time, and thus has a shelve life (a few years), how quickly this happens depends on the particular compound. It also suffers from a “pump-out” effect where the TIM, IHS and heat sink react (expand at different rates) in response to heat (pc powered off vs on, or under stress) causing movement, the thermal compound can move more freely and is slowly redistributed, or pumped-out, between the IHS and heat sink resulting in air pockets/reduced thermal conductivity. The wetter the compound (typically the more high performing), the worse this effect becomes. Worst case it happens within a year, best case >10 years. Sometimes “pump-out” is mislabeled as “dry out”, real “dry out” only happens with the cheapest thermal pasts, where the moisture inside the thermal compound slowly evaporates, and often takes (>5) years.

In practice there is no good way to know when thermal paste should be replaced, generally as long as there are no immediate temperature problem re-application is not required. Some people like to, preemptively, re-apply it every 1-2 years, this is not required.

To remove (non liquid metal) thermal paste use microfiber cloth/… with isopropyl rubbing alcohol, +90% is advised but lower will work as well.

If the thermal compound is conductive be very carful to not apply too much as it will be squeezed out possibly causing shorts, thus HAS to be cleaned-up very thoroughly.

Liquid metal thermal paste (non-toxic BUT corrosive) performs the best (a few °C, especially at higher temperatures) BUT is hard to work with as makes aluminum brittle, reacts with copper (non-destructively but it dries out) and is electrically conductive. Thus if you make a mistake during application it may become costly very quickly. Due to the limited performance gain generally not worth the hassle for our use-case.

Thermal pad

Thermal pads are cut to the size of the IHS and heat sink. Quality of the pads is important to come close to the performance of thermal paste. They are easier to work with (fool proof) and require no maintenance for nearly the same performance.

Thermal pads are typically used in server/HPC (high-performance computing) as they are easy to apply, consistent, have no “pump-out” effect and never require maintenance. While their performance is only marginally worse (a few °C).

The come in different thickness, for CPU less is better. For GPU check carefully what you need. Too slim pads will not make proper contact impacting performance, too thick and they might not fit.

Delidding

tl;dr not recommended, only for confident advanced users. Results vary but are significant, 5-15 °C. Voids warranty.

The CPU itself is a die (integrated circuit), mounted on an circuit board covered by an integrated heat spreader (IHS) to dissipate the heat (and pressure) over a larger area to a cooler. Between the die and IHS TIM (Thermal Interface Material) is applied to aid heat transfer. The smoother the IHS the better the heat transfer to the cooler.

Source: anandtech.com

Link: Delidding AMD Ryzen

Delidding refers to replacing the stock TIM with a better performing one and optionally replacing the IHS with an after market one which is typically a bit larger and smoother improving thermal conductivity resulting in better cooling performance. There exists out-of-the-box kits with everything you need. Expect a 5-15 °C improvement but your mileage may vary. Delidding is effective because CPU manufactures make CPUs at scale, fast, and there are trade-offs to be made in manufacturing due to costs and manufacturing speed.

Whether delidding is worth it depends on the product line, if the chip is soldered to the IHS there will be no/negative gains.

Specialty delidding kits exists to make it easier/reduce the risk, albeit will drive the cost up.

This is definitely only for dedicated and advanced users but gives significant results. The technique comes from extreme overclocking.

Direct die cooling

tl;dr not recommended, not worth the risk. Voids warranty.

Similar to delidding but in this case the IHS is simply left out and the cooler is attached directly to the die (still using TIM). Improving thermal conductivity. It comes with a high risk as applying too much pressure will break the die/CPU/GPU. Some GPU manufactures apply this technique out of the box.

Specialized/modified coolers/mounting brackets are required to mount (air) coolers directly to the die. Possibly the CPU socket (on the motherboard) most be removed as well.

This is only for the most advanced users. This technique comes from extreme overclocking.

Polishing

tl;dr not recommended, not worth the effort. Voids warranty.

As the default IHS is often not perfectly smooth, and the smoother the surface the better the thermal conductivity with the CPU cooler (less TIM required), the IHS can be polished to be more flat. Some products suffer more then others, but generally are fairly good.

Consult a guide on how to do this.

The same applies to the bottom of the cooler, but these are usually already smooth/flat enough out of the box.

This technique comes from overclocking.

GPU modifications

Deshrouding

tl;dr may significantly reduce noise and GPU temperatures. Results depend on your GPU model. Voids warranty.

Deshrouding means removing the plastic shroud (guiding air flow, and for aesthetics) and original fans of a GPU cooler and replacing it by regular 92/120/140mm (static pressure) fans (usually with zip-ties). The air flow of the original (slim, usually 92mm) fans are inferior to normal case fans and therefor the cooling performance can be improved (typically 10-30 °C) leading to lower noise levels (running at the original temperature). The fans should blow air directly into the heat-sink and may be connected to the GPU (sometimes requiring a 4-pin CRJ adapter) or motherboard. An off the shelve GPU exists which does this as well (and has excellent results).

Search for a guide if you are unsure. Usually it is easy to do but may depend on your particular GPU model as some shrouds are harder to remove or have metal gaps/connectors sticking out of the heat-sink which prevents mounting the new fans flush to the heat-sink. Nothing a bit of cutting cannot resolve.

If you have a small case it might be tempting to install the fans in the case itself, below the GPU, instead of directly attaching them to the heat-sink of the GPU. It will typically leave a gap of a few cm between fan and heat-sink. This is a bad idea as cooling performance will be significantly worse, not all air will move over the heatsink and resulting in a lower static pressure. Cooling performance might even be lower the with the original cooler. However air ducts/shrouds can resolve this problem.

This modification allows one a wider range of GPUs as their, out of the box, noise level become less important. The bigger/thicker the original heat sink the better the expected result.

Popular, and sometimes required, modification for SFF cases to keep GPU temperatures at bay.

Repasting / replace, or add, thermal pads

tl;dr may notably reduce temperatures. Typically not required. Results depend on your GPU model. Voids warranty.

Some GPU models come with suboptimal thermal pads and/or cooling paste (TIM). Swapping them out for better performing ones might save 5-10 °C. However the effectiveness very much depends on your GPU model/brand.

When using thermal pads check carefully what you thickness you need. Too slim pads will not make proper contact impacting performance, too thick and they might not fit.

Configuring the software

tl;dr configure the fan curves to only speed up the fans when required, resulting in less noise.

PWM fans are connected to your motherboard can be controlled through software. Typically the fan speed is made dependent on a sensor value, e.g. CPU temperature. One can configure a “curve” to specify for each temperature how fast the fan should spin. For a silent system one should configure the fans as slow as possible (<50% at all times, or what is inaudible for your noise floor) without thermal throttling the system. What the best curve is for you system will require some trial and error (if the room temperature differs a lot with the seasons take this into account as well).

Fan curves can be configured in the bios of your motherboard, which will require a reboot every time you want to adjust them, which is pretty annoying. Alternatively software can be used which can be configured on the fly, for window FanControl is an excellent example and more powerful then the motherboard’s bios.

By default the fans will spin at full speed.

Lowering the room temperature

tl;dr ventilate the room.

The lower the room temperature the more effective air cooling will be. Airconditioning , open doors and windows can all help to lower the temperature in the room. Depending on your system it might heat up a closed off room measurably by a few degrees over the span of a few hours. Larger rooms (more air volume) take longer to heat up.
Creating natural airflow (open window and open door) may also help.

However this will not turn a noisy system into a silent system, it typically will only help a few degrees depending on the weather. An exception is if you have a HVAC system installed, in which case you want to avoid open windows.

Out-of-scope solutions

These solutions do not fit the use-case but are worth mentioning never the less.

Remove the system from the room

tl;dr very effective and for audiophiles often the only option. Feasibility depends on your living space/house.

Removing the source of the sound will always be more effective then making it more silent. There are many ways how a computer can be moved to another room, depending on the distance and use-case. Going into detail is far our of scope for this post. Some options are: using thunderbolt + dock, using USB cable + dock, using remote desktop, …

Using a (remote) virtual machine/server is also an option especially for productivity. The server can reside in a utility room being noisy while not bothering anybody.

Liquid (water) cooling

tl;dr more effective, and can be made more quiet, then air cooling. More maintenance.

More efficient then air cooling, water is pumped over hot components (transferring heat to the water) and hot water is cooled through a radiator (typically with fans) where heat is again transferred, to the air. The more radiator surface the easier it is to cool and the slower the fans have to spin. One can use many low noise fans, <15dB and still have stellar cooling performance. Pump noise is a concern through, but otherwise whisper quiet systems can be achieved. If the water pressure is too high, or the water reservoir is not optimal, the flow of water can become audible as well.

This section is by no means complete and could be an post on its own which is out of scope.

Water cooled systems do require periodic maintenance (changing the water, …). More then air cooling.


  1. manufactures usually assume 40-65 °C working environments (air temperature in a computer case). ↩︎

  2. only becomes significant at >30 °C and typically there is not much one can do about it ↩︎

  3. their location matters as well, evidently they should not be placed in direct sunlight as it will greatly reduce their efficiency, or worst case heat them up instead ↩︎

  4. the higher the air temperature the lower the difference between the material (heat-sink) and the air and which slows down convection. Humidity also plays a roll, as it impacts the heat capacity (thermal mass) of the air (). Also passive cooled system can never cool the system below the air temperature. ↩︎

  5. this means mesh panel at the bottom to provide fresh cold air, with high enough feet from the floor, and a mesh panel at the top to exhaust the hot air. Metal side panels are more effective then glass and plexiglass is the worst option. Noise isolation panels are to be avoided (and unnecessary in passive systems anyway). Air filter should be removed to enhance natural convection as much as possible (and again are unnecessary in passive systems anyway). The best results are achieved if the air can move as free as possible. The case itself can also double as a heat sink, this is especially applicable for full aluminium cases (which typically consists of thicker sheets then steel cases and thus have more heat capacity). Aluminium also has a good heat transfer coefficient (meaning it easily exchanges heat, in this case with the air) ↩︎

  6. there should be enough air volume around the CPU and the GPU should be placed as far as possible from the CPU to no warm up the same air, and thus, influencing the cooling capacity of one-other ↩︎

  7. 80 Plus label is a crude label which says nothing about quality of the power output to your system or noise level. The new Cybernetics certifications is much more extended and includes a different noise label. ↩︎

  8. fun fact, the ATX standard is created, and still maintained, by Intel ↩︎

  9. there is no hard definition what is considered small form factor, some say <10L, some <20 and some <25L. <20L seems a good middleground. One could argue anything only fitting ITX motherboards however there are big cases, e.g. Torrent Fractal Nano ~34L, which no one would label SFF but only fits ITX. ↩︎

  10. 180mm fans are rather rare thus aftermarket options are very limited. Fortunately the Dynamic X2 GP-18 PWM performs well and is quiet at the lowest setting (while still moving a lot of air) ↩︎

  11. be mindful the biggest CPU coolers might not fit if the CPU socket (not standardized for ITX motherboards) it might bump into the PSU shroud ↩︎

  12. even though the case is massive for ITX it does not support regular 140mm fans under a 3 slot GPU (without modifications). Very unfortunate. ↩︎

Noticed an error in this post? Corrections are appreciated.

© Nelis Oostens