Keep Your Audio PC Cool Using Quiet Fans

Tips & Techniques

Published in SOS August 2011
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Technique : PC Musician

With processors getting ever faster — and running ever hotter — what can you do to get the best performance from your PC without making it sound like a washing machine on full spin?

Pete Gardner

Keep Your Audio PC Cool Using Quiet Fans

In a world full of noise, silence is a precious commodity. Unwanted noise can find its way on to your recordings, result in poor mix decisions, and simply irritate you. In a modern studio, one of the biggest culprits can be your DAW PC, so in this article, I'll tell you all you need to know to stop it being a noisy nuisance.

Case Law

Before we consider what individual components you might want to upgrade, tweak or replace, it's worth taking a step back, and thinking generally about what makes for good practice in computer case layout and why. Whether you're upgrading an older PC or trying to turbocharge a more recent off‑the‑shelf model, the key challenge is to combine high performance (ie. fast processors, lots of RAM and plenty of hard‑disk storage) with effective, quiet cooling. Unfortunately, the simplest and cheapest means of cooling is using fans to blow or draw air across hot components, and this has the potential to generate a lot of noise. The smaller a fan is, the faster it has to spin to move a given amount of air, and A mess of cables inside your computer case will inhibit airflow — so get the cable clips out and tidy them up!A mess of cables inside your computer case will inhibit airflow — so get the cable clips out and tidy them up!the faster it spins, the more noise it makes. A case with a good clean layout, which encourages airflow across your components, can make the job of cooling the system a whole deal easier — so that's a good starting point when trying to optimise any future upgrade.

In smaller tower cases you can get away with fewer fans, as there's simply less air inside to deal with than there is in larger designs. The down side is that by packing in a larger number of drives and cards into the tight space you will inhibit the airflow, leading to a quicker and potentially more problematic build-up of heat.

A larger, tower-style case allows the flow of a greater volume of air over the components, helping to keep the ambient temperature down. This also has a down side, though, in that you'll need either more or faster fans in order to drive that volume of air. Either way, you'll increase the noise levels. This is why the ability of some large cases to accommodate extremely slow, large (230mm) fans can be very beneficial in audio PCs.

A rackmount PC might seem tempting in the studio, but standard 4U ones can't always accommodate the latest, largest CPU heatsinks, and airflow can be inhibited.A rackmount PC might seem tempting in the studio, but standard 4U ones can't always accommodate the latest, largest CPU heatsinks, and airflow can be inhibited.Keep Your Audio PC Cool Using Quiet FansRackmountable PCs appeal to a lot of studio users for obvious reasons, and typical rackmount cases are capable of handling mid‑range system specifications with ease. However, I've found that some of the high power‑use, high‑end systems can prove problematic when it comes to cooling if mounted in a rack case. Due to the layout of the back plate, 4U rack cases only have room for 80mm fans on the rear, and not every design has a mounting point for a fan at the front. This makes quiet cooling tricky. Furthermore, the CPU‑cooling heatsinks that would be most effective in a free-standing solution simply won't fit with the low ceiling of the 4U rack case. Working with a 5U rack case can be easier, as the extra space provides room for multiple 120mm fans and more effective heatsinks, should you consider upgrading components in the future.

Exit Planet Dust

If you have an older system that hasn't been inspected internally for a while, it's well worth taking the side off the case and examining the fans on the case and on the CPU's heatsink. You're looking for dust, which can build up in computer systems surprisingly fast.

A vent blocked by dust will not only make the job of blowing air around the case more difficult: it will cause the internals of the case to heat up, and any fans that are temperature-controlled, such as the ones on CPU and GPU heatsinks, will spin faster to cool those processors. In short: the more dust, the hotter the case, the faster the fans — and the greater the noise generated by your PC. You can clean fans by using a soft‑haired brush to loosen any dirt around them, before using a canister of compressed air to blow any dust out of the case. However, avoid spraying the air directly onto electrical components, as small amounts of propellant can be forced from the canister with the air.

If you find at this point that your system is a nest of cables, get some cable ties and arrange the various wires neatly in the case so that they're not hanging loose. Cables laid out like spaghetti don't have wonderful aerodynamic properties! Tidying them up will mean they exert less resistance, and this will help to get more air across your components for each turn of your fans. Tie bases (small plastic hooks that you can fix to the case) enable you to attach cable ties cleanly to the side of the case.

Treat Noise, Or Remove It At Source?

Dust will inhibit the performance of fans, and components will get warmer, requiring the fans to work harder and make more noise for the same amount of cooling. So clean your machine regularly!Dust will inhibit the performance of fans, and components will get warmer, requiring the fans to work harder and make more noise for the same amount of cooling. So clean your machine regularly!

Once you have your case looking clean and orderly, it's time to think about where any remaining noise is coming from, and whether to tackle the problem by absorbing the noise or trying to reduce the racket the computer is making in the first place. Often, of course, a combination of both approaches is necessary.

Case soundproofing material can be added to the inside of the system, but as the material is usually quite thin, it may only help attenuate higher frequencies, and it will still leave some noise leaking out of any exposed vents and ports. After all, if the case were airtight, you couldn't cool the components effectively! So while this can improve things, it's no magic bullet.

One notable advantage of installing this sort of soundproofing material, though, is that it adds mass to the side panel, and this in turn can help reduce vibrational noise. This can be particularly beneficial with some of the less expensive, thinner‑shelled cases. While it is not a catch‑all solution to your noise issues, then, you should certainly consider adding such 'soundproofing' to your case.

Usually, the more effective solution is to consider each individual source of noise within your typical system and work out how to eliminate the source, or reduce the level of noise it generates. You'll make the biggest improvement quickest if you approach the noise‑elimination process in order of the sound sources that are most likely to be heard from your working position, and work to reduce them in order of intrusiveness.

Fan Club

The aim in laying out your case is to encourage good airflow across the components. Cooler air is drawn in at the bottom of a tower case. As it warms it rises and is drawn out of the case by the fans at the top rear.The aim in laying out your case is to encourage good airflow across the components. Cooler air is drawn in at the bottom of a tower case. As it warms it rises and is drawn out of the case by the fans at the top rear.

Whether the case fans have the dubious honour of occupying number one slot in the PC‑noise hall of shame will normally come down to the case layout itself, for the reasons described above. But while many fans are described as 'quiet' or 'silent' by their manufacturers, not all of them are created equal in this respect...

When fitting replacement fans, you should first consider the direction in which air is being pulled through the case. The aim is to encourage a good front-to-rear air flow inside, and best practice in a typical tower case would have the fans at the front and bottom of the case, pulling air in to the system. Natural convection then helps to move heat up to the top rear corner of the case, so fans at the rear and on top act as an exhaust, quickly removing the warmer air from the system. To help keep the system clean, it can be a good idea to get fine mesh filters for the inlet fans; a number of firms supply products for this purpose.

When choosing fans for your system, be warned that the quoted fan‑speed figure can be misleading. There are few fans — even among those sold specifically as low‑speed models — that are truly whisper‑quiet at their full speed. In practice, best results are usually obtained from those fans that ship with a voltage restrictor, allowing you to bring the fan speed down further than the standard setting. Voltage restrictors come in a few different forms, but they all work by simply reducing the voltage in the circuit feeding the fan, which in turn lowers the fan speed. Some of the better fans come with a selection of different cables with built‑in resistors. Typically, a standard 12V fan can safely be run on 7 or 9V in this way. The other style of voltage restrictor you're likely to come across is a fan controller with a dial, which can be adjusted to vary the available voltage from as low as 5V up to the maximum 12V. There are various commercial products that allow you to slow the speed of your case and CPU fans.There are various commercial products that allow you to slow the speed of your case and CPU fans.

If you inspect the data sheets some manufacturers publish, you'll notice that fans tend to have an increased gain in motor noise over the upper 25 percent of the rated speed. By running these fans at 60 or even 70 percent of that speed, it's possible in some cases to reduce the noise they produce by up to 50 percent. In instances like this, it can prove more effective to use multiple fans running at lower speeds, so that you can get full coverage of all of the components with less cost to the overall noise floor of the system.

Voltage modifications like these can be carried out to any fan, but not every fan can handle low-voltage starts. Most need around 5V to get them into motion, some even more, so any kind of adjustment to your cooling system in this way should be monitored for a few power‑up sequences after fitting, just to ensure that the fans are starting each time and will continue to help cool the machine. Choosing fans with voltage restrictors included in the price is a good sign that they will have been fully tested to work at the selected voltages. Having a selection of voltages to work with can help you fine-tune the effectiveness and noise levels, in a process that I'll cover later on.

Fans don't only create airborne noise: they can also transmit vibration to the case through their mounting. Rubber‑based screw replacements can be used to mount the fan. These can help reduce vibration transference to the chassis and thus reduce rattles from the side panels.

Graphics Card

Graphics cards can be some of the most annoying sources of noise. Larger fans are better than small — but the graphics demands of audio software are not significant, and it's better to choose a cheap and affordable card that uses only a heatsink, as they emit no noise.Graphics cards can be some of the most annoying sources of noise. Larger fans are better than small — but the graphics demands of audio software are not significant, and it's better to choose a cheap and affordable card that uses only a heatsink, as they emit no noise.Keep Your Audio PC Cool Using Quiet FansCase fans can stand out as the worst noise producers, simply due to the numbers found in typical system, but the graphics‑card fan can rival them simply by being the most irritating! If you have a fan on a graphics card, it will tend to be smaller than the rest of the system fans, and so it will be more likely to emit a higher-pitched tone that will be noticeable to the listener. This is why it is always best to specify a passively cooled graphics card in your initial purchase where this is possible. If you do find yourself with a fan‑based card in your system but you have only modest performance requirements, and the card is creating more noise than you'd like, then a replacement card is often the only real option. That might sound daunting, but it's not expensive: good‑quality passive graphics cards that meet all daily application display needs on a non‑gaming system start at around £30$50.

On the other hand, if you feel you need a mid‑range or high‑end card, perhaps for the use of CUDA‑based plug‑ins, there are various after‑market cooling options for a large variety of graphics card models. Most of these solutions offer an increase of fan size and a reduction in fan rotation speed, and often achieve far better cooling and noise levels than the stock fans.

Alternatively, it may be possible to restrict the speed of an existing graphics‑card fan. There are software applications that can do this, including AMD's Catalyst control panel and a number of third‑party utilities. However, when using them, be sure to monitor the graphics card's temperature in use after any adjustments have been made, to ensure the specified operating maximums are not exceeded in use.

CPU Heatsink

Heat is conducted away from the CPU by a finned construction called a heatsink, and this can prove a bottleneck for quiet cooling when a large project puts the CPU under load, causing it to heat up and the fan to speed up to compensate. Improved replacement designs from many companies increase the area that the heat has to dissipate from. In conjunction with larger, slower fans of up to 120mm or even 140mm in size, the more efficient transfer of heat over a larger surface area leads to more effective cooling, with the CPU fan being able to run slower in order to maintain the desired temperatures.

It's preferable to connect the fan on the heatsink to the CPU header on the board (rather than directly to the PSU), allowing the computer to adjust the airflow to the CPU should it heat up under load. Some BIOSes will allow the user to set 'threshold' temperatures for the fans to kick in, allow for more control over the cooling and noise levels created by the fan. This should always be monitored after setting, to ensure that good average system temperatures are maintained.

When setting the heatsink up, you should always ensure that the airflow is in line with the rest of the system, so the fan itself should be positioned to blow air towards the nearest exhaust vent, either at the rear or on the ceiling of the case.

Power Supply

The quality of power-supply fans varies greatly, from almost inaudible even under a high load to downright irritating when the system is just sitting idle! A number of firms do low-noise solutions, so if you find yourself needing to replace a PSU at any point, a bit of research into the noise and performance levels of current models can go a long way. However, be careful not to buy a brand X 750W PSU on the grounds that the brand X 550W model has been getting good ratings: a large number of firms tend to subcontract out the production of various models to different manufactures, which means that even units within the same range can have vastly different noise signatures.

If your current PSU is beginning to make more noise than it used to, it can once more be worth blowing it out with compressed air to remove dust, although in this instance, you should avoid pushing anything past the protective grill.

Whilst it's not completely unheard of to modify power supplies to use different fans, a lot of low and mid-range models have the fans hard‑wired to the circuit boards, and others may use non-standard connectors. The biggest concern when considering this is that the capacitors inside a PSU can hold a dangerous charge for long durations. This can deliver a severe enough shock to do you serious harm. It is highly advisable to never take a computer's power supply apart unless you are 100 percent sure of what you can and cannot touch safely, as well as understanding exactly which components will do you harm.

Hard Drives

Hard drives are another component where research can pay dividends when upgrading, as some models have a more intrusive noise signature than others. If you find yourself with a drive that is too noisy, there are a couple of options that can help. Rubber mounts can be used to decouple a noisy drive from the case, resulting in fewer vibrations being transferred to the side panels from the drive. The other source of noise from a hard drive can be the motor of the read head moving about. You can buy dual-function drive-bay coolers that will place your hard drive in a 'coffin' that conducts heat and reduces audible noise levels. These also have the additional benefits of the grommets mentioned previously.

System Testing

Once you've chosen and fitted your cooling components, it's important to stress-test the system to ensure the new setup can safely handle high loads that might occur during use. You can do this by placing the CPU under full load using 'stress tester' software, and measuring the temperatures achieved in use. Popular tools include free utilities such as Prime 95 and OCCT, which should be used in conjunction with other monitoring software utilities such as Realtemp or Coretemp so that you can observe the CPU temperature over a period of time as it is stress-tested. You'll find the maximum recommended CPU operating temperatures for CPUs in the manufacturer's specifications, and you should try to ensure that the chips remain at least 20 degrees below the specified maximum safe level when under full load, in order to allow for natural changes in cooling performance between system maintenance checks.

It's at this point that fans with adjustable voltage restrictors can come in handy, as you can lower the speed if you have the temperature headroom, or increase it if you need to bring heat levels down further.

With a quick look and a bit of careful consideration, you can quickly pinpoint and eliminate intrusive noise sources. Once you've done this, though, a regular maintenance routine of a quick clean-out every few months will help keep your system running at its optimum for many years to come.  

Liquid Refreshment?

Water‑cooling might seem like an attractive option — but while such systems are very effective, they aren't necessarily quiet!Water‑cooling might seem like an attractive option — but while such systems are very effective, they aren't necessarily quiet!One question that often arises is about the effectiveness of water cooling. Water cooling works by moving heat away from the source point to the outer edges of the case, where radiators are attached. Air is forced between the fins of these radiators to remove heat from the water being passed through. Because traditional air coolers work by spreading heat over a large area, it takes longer for heat to dissipate from a larger heatsink than from a small water block that has the heat continuously absorbed away from it. This makes water cooling more effective. Water‑cooled CPU and GPU options are common, and there have even been attachments for cooling RAM, the motherboard chipset and hard drives

Although this sort of setup can be perfect for a high‑performance gaming system, however, it is often not ideal for an audio workstation. The down side is that the radiators in water‑cooling systems often have far more, thinner fins than the heatsinks they replace, meaning more air pressure is required. This is achieved by placing faster — and therefore noisier — fans right next to the vents. Other possible acoustic problems include added motor noise from the pump itself, and even if you've managed to reduce component noise to an acceptable level, you might still hear the trickling of water round the system.

Water cooling works best at the point where air cooling fails in controlling the heat. With the current generation of CPUs, air cooling can do a superb job, even if you're overclocking the system (within reasonable levels). Notably, the main focal point for water cooling has currently moved its focus to high-end graphics and video systems, as these can generate a lot of both heat and noise when performance is pushed.

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