5 Things To Think About When Buying A New PC - Part 2 - Noise

08-19-2014 07:58 AM

In this 5 part series Robin Vincent helps those wanting to buy a Windows machine find the best machine for the job. In part 1 he looks at the heart of the Windows PC the processor, in this seconrd part he talks about the important consideration of noise in a recording studio.
It’s remarkable how much noise we’re prepared to put up with from our computers. If you’re not fortunate enough to have a machine room in which to stack up all the noisy gear then computer noise can be seriously detrimental to your creative environment, not to mention your state of mind. You don’t have to put up with it. If you need a system that’s going to give you every ounce of power then some noise may be inevitable but let’s look at ways in which we can minimise it so that ideally it sits somewhere below our studio noise floor.
There are three main sources of noise in a PC: cooling fans, PSU and hard drives.
Cooling Fans

You’ll find cooling fans on the CPU heatsink, often in the front and back of the case, and usually on the graphics card if you have one. The CPU is the hottest part of the system and so any cooling solution is designed to pull heat away from that area. This is usually some sort of metal heatsink on which is fixed a fast moving fan to pull the heat away or to blow cool air upon it. Case fans act as a way of bringing cold air in and blowing hot air out, ideally in a single direction. High performance graphics card have a GPU which also gets very hot and requires its own cooling. So that’s potentially a lot of fans trying to move air about as quickly as possible. The noise you hear is not that of the fan’s mechanism (if your fan squeaks then it’s time to replace it) but rather of the air being moved.
There are two factors that dictate the amount of noise a fan will make – size and speed. The smaller the fan and the faster the fan the louder the noise will be. Larger fins on a fan will move more air so you can use a 120mm fan running slower to move the same amount of air as an 80mm fan running faster. So, what you need to move the maximum amount of air with the minimum of noise are large, slow moving fans. There are all sorts of factors involved in fan design in terms of efficiency and noise but the key ones are rotation speed measured in RPM and airflow measured in cubic feet per minute (CFM).
Let’s take two fans from Austrian ultra-quiet fan makers Noctua as a comparison.

  • 80mm NF-R8: Airflow 31.2CFM Noise 17 dBA Max Speed 1800rpm
  • 120mm NF-S12B: Airflow 33.4CFM Noise 6.8dBA Max Speed 700rpm

I’m a big fan of your work
As you can see the 120mm fan is moving slower, making less noise while moving more air than the 80mm fan. Not all fans are created equal but replacing 80mm fans with 120mm fans can reduce the noise level significantly, especially if you use really good ones like the Noctua. However, when the computer world talks about “quiet” it’s not talking about our concepts of studio quietness and so you may find that even with 120mm fans your system is still too noisy. The default speed of most 120mm fans (unlike the S12B above) is 2000rpm. The trick is to get your fans down to around 1000rpm which is when they tend to drop to a whisper. Your computers BIOS can play havoc with the fan speed where it likes to speed fans up as soon as the temperature rises, which would normally be a great feature, but on a system built for audio the last thing you need is an increase in noise level. The BIOS should allow you to fix fan speeds manually or set them to ignore temperature changes. One other way to achieve the same result is to use an inline resistor to restrict the top speed of fan – that way the fans can speed up a bit if necessary but never become too audible.
If your system came with a stock Intel CPU cooler and fan then you can usually replace this with a much bigger heatsink and fan in order to improve the cooling and reduce the noise. This can be very fiddly depending on the size of your case and the component layout. Watercooling is another possibility, not in a scary water-and-electricity-potential-nightmare sort of way but in a simple, self-contained CPU water block and radiator. This has the advantage of moving the CPU heat to the edge of the case and then uses a large fan to cool the radiator. Units like the Corsair Hydro range are easy to install, maintenance free and put less stress on a motherboard than a huge, heavy heatsink.
GPU fans can be much more troublesome. Then tend to be very small and run very fast, particularly when stressed. Most have some sort of speed control that keeps them quiet until the card heats up but there is very little you can do to restrict the speed or noise coming from those fans. There are some custom fan kits and water coolers but they require voiding warranties and getting your hands dirtier than I’d advise. You are better off trying to keep the area around the card as cool as possible to reduce the need for the fan to come on at all. Modern CPUs actually have a high performance GPU built in which are kept cool by the CPU cooler and so going without a discrete graphics card is one way of avoiding that potential noise issue.
PSU noise

The power supply also needs cooling and so contains a fan. Nowadays these tend to be large 120mm fans that fit at the side of the PSU rather than the older ones with 80mm fans at the rear. If yours is really noisy then consider replacing it with one designed to be quiet. You can also get whining or electrical noise from some of the components, in which case replacing it is your only option as opening up a PSU would void the warranty and can be potentially dangerous. Replacing a PSU can be fiddly as the power cables go to every drive in the system and to two places on the motherboard – make sure you have access to all those areas before attempting to replace it.

Hard Drives

The noise of a hard drive is very familiar and actually quite comforting when you hit the power button on your computer to boot it up. However, when tracking, loading samples or streaming video the chattering noise can be a trifle penetrating. A common noise reducing option is to put the drives inside acoustically lined enclosures and then mount them in 5 ¼ inch bays. These can work well but don’t allow for much in the way of cooling and so there is a danger of baking your data. A simpler but not quite as effective solution is to use anti-vibration mounts or cradles which prevent the vibration from the drives being transferred and amplified by the case. The best solution of course is to move to solid state drives (SSD) which have no moving parts and so generate no noise at all and very little heat.

Intel continue to develop more efficient and cooler mobile processors but the more powerful ones still require active cooling. The size of a laptop shell means that the fans are going to be small and noisy and if you’re running DAW software then they are likely to be on all the time. I’ve run lots of experiments with cooling stands, bottom mounted fans and other laptop cooling solutions Even with powering a large 120mm fan at high speed directly into the vents I couldn’t get the temperature to drop more than a degree or two. What cooling stands are good for is ensuring good air flow across the sides and bottom of the laptop. Placing your laptop on an uneven surface, such as a lap or a chair, can block some of the vents making it overheat or have to turn the fans on full blast. If noise is your main concern when buying a laptop then you should aim for a lower powered processor. With i3 dual cores the fan rarely comes on during normal use; with i5 dual cores it comes on when you start to stress it; but with quad core i7 processors it’ll kick in most of the time.
Cooling Is Vital

With any attempts at noise reduction it is absolutely vital that the system is still adequately cooled. Reducing fan speeds and putting drives in enclosures could allow heat to build up inside the system and end up damaging components or reducing their lives – air needs to flow. So after making any adjustments you should use something like Prime95 and HWMonitor to run your CPU at 100% and monitor the temperatures. Intel CPUs will shut down when they get too hot but as a rough guide 100 degrees C is “bad”. The CPU should idle at around 30-40 degrees and settle at around 70-80 degrees when fully loaded. With careful adjustment, making sure your air flows in one direction, you can find a sweet spot between too much noise and not enough cooling.
I suppose you think you’re cool

If noise reduction is simply not good enough then complete silence is a genuine possibility. There are cases that can act as a passive heatsink and transfer the CPU heat to the outside of the system. These have to use the lower powered “S” range of processors (see previous article) in order to keep the heat output under control but provided there is air flowing around the case it can work very well. At Molten Music Technology our Muse range uses cases from Streamcom.com. When combined with an external power supply and SSD drives you can have a very microphone friendly studio system. It is slightly disconcerting though not to hear anything at all when you press the power button.
Helpful Links

About The Author

Robin Vincent is a veteran of the computer music industry. Back in the 1990’s he ran the PC Product department at Turnkey, released a couple books on the subject and helped design the Carillon AC-1 audio PC and bring it to market. From 2006 he ran the UK operation of audio PC manufacturer “Rain Computers” and from 2013 he formed Molten Music Technology to continue building audio PC’s under his own steam. This independence enabled him to team up with Pro Tools Expert’s own Neil Hester to create The Pro Tools PC, the only computer designed, built and supported exclusively for the use of Pro Tools. He lives with his wife and three young kids in the wilds of Norfolk where he likes to create meditative music and produce electronic soundscapes for Cathedrals.
For more information visit our support page kindly sponsored by Pro Tools PC