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Topic Title: Guide to Quieting a Noisy PC
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Created On: 04/12/2004 10:32 PM
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 04/12/2004 10:32 PM
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Troll Hunter

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A friend of mine once had a machine which was so loud the sound of it was mistaken for a vacuum cleaner. About the same machine, it was said to me one time, "I was downstairs, and I heard it shut off." Do either of those sound familiar? Of course, how much noise is too much is somewhat subjective. The noise obviously didn't bother my friend, but would have driven me crazy within a matter of hours. The purpose of this guide is to help those interested to kill the noise and get out of the headache zone.

Before I get to the actual tips though, I should give a disclaimer that my personal attitude towards soundproofing is that it should not compromise performance of the system. There's plenty of ways you can underclock your system which will drastically reduce the amount of heat dissipated(and reduce performance along with it). Less heat means you can use a smaller amount of airflow to dissipate the heat. Less airflow often means less noise. However, I really can't stand to do such a thing. In any case, most of the stuff covered in this guide(except for some stuff near the end) will apply to either course of action. If you do decide to quiet the machine by means of underclocking, it'll make your life a lot easier if you build the system around an AMD processor. Currently AMD processors produce less heat in general, and you'll probably lose less performance by dropping the clock speed of an AMD processor than you would an Intel counterpart. Lastly, it'll help while applying the tips below to have some brief background on how sound works and how it's measured(and maybe help in creating a few future tips of your own ).

Sound has two basic modes of transportation: though the air in the form of sound waves, or though structures in the form of vibration. When an object vibrates outward it displaces air particles pushing them away from the object. This forces the air particles to compress causing an area of high air pressure. When the vibrations retract, the air particles are allowed to spread out creating an adjacent area of low air pressure(the term for this is rarefaction). This series of alternating high and low air pressure areas are what's referred to as a sound wave. When a sound wave hits your ear the various structures in your ear do their job of morphing pressure differences into electrical impulses which are sent to your brain and interpreted as noise. When a sound wave hits another structure it can energize the structure causing it to vibrate which starts the whole cycle over again.

It follows then that attempts at soundproofing your computer should be aimed at controlling the airflow in and around your machine and suppressing the vibration caused by its components. It's also important to know what type of noise you're dealing with. What works for stopping one type of noise doesn't necessarily work for stopping the other.

As I mentioned at the start of this guide, perception of sound levels is somewhat subjective which can make measuring sound levels tricky. Probably the most commonly used units for measuring sound are decibels. A common misconception is that decibels are absolute units such as feet or meters are(one meter is one meter no matter what you're measuring). What decibels really represent though is a ratio of two levels of power. That means, before you actually start measuring something using decibels, you need a second value that you can use for comparison. Let’s say you have two sets of speakers, and you want to find out how much more sound one puts out compared to the other. In this case, you would use the sound of one set of speakers as the reference level, and measure the other speakers against it. If you got the result of 0 decibels, it wouldn't mean that one of those speakers is silent. It would mean there is no significant difference between the two. In the case of items like computer components, most of that can probably be safely forgotten since the reference level used is often very close to zero(usually it's 20 micropascals, a pressure level which is on the lower limit of human hearing). That gives a more concrete idea on just how much noise a single component produces.

Notice above, when I defined a decibel I said it was a ratio of powers not a ratio of "loudness"(did I mention measuring sound levels could be tricky?). A full explanation is outside the scope of the guide, but suffice it to say that our ears don't respond to all frequencies equally. Also, and perhaps most importantly, decibels are measured on a logarithmic scale; meaning a difference of 10 decibels does not mean the sound will be ten times as loud. Roughly, it takes a difference of 10 decibels for the sound to be heard as twice as loud.

With the background out of the way, it's time to move on to the specific things that can be done to kill the noise of a noisy PC. There's not much difference between heatsink fans and case fans really, so most of the stuff covered below applies to both. The only big difference is that insulating the case(which I'll talk more about in a bit) will help much more in controlling noise from a heatsink fan than it will noise from case fans(noise from case fans already has a straight shot to the outside world). Despite what you might have seen elsewhere in mid tower cases that have 5, 6, or 17 case fans(not kidding...), you really don't need more than two in order to have sufficient airflow passing though the case. If you have a lot of case fans in your machine, but none of them are very loud individually, then you might be able to get away with just using less of them. If some of them are a bit loud, you can replace them with quieter fans. Papst fans are at the top of the list followed by Panaflo(both can be found at Plycon' ">http://www.plycon.com). These two particular types of fans use a different kind of bearing, and also spin at a slower rate(fans that use conventional ball bearings often won't be your best friends when trying to soundproof your PC). Slower rotations reduce both bearing noise and noise created by air turbulence. However, fans that spin slower will also produce less airflow which will lead to higher temperatures. One way around that is to use larger fans(such as 120mm fans) which due to their greater surface area can spin at a slower rate and still move the same amount of air. Another solution is to get temperature sensitive fans which will speed up as temperatures increase and slow down as they decrease. The stamped metal fan grills that are built right into the sides of the case can also be a source of noise since they often cause a significant amount of resistance(resistance causes turbulance which causes noise). The solution to that is to get out your dremel(no person without one can rightly call themselves a modder ) and simply cut it out. In order to keep fingers and curious pets out of harms way(that is, unless you don't care about your fingers or pets...) the fan grills can be replaced with grills that are less problematic. The chromed ring grills found on some power supplies are probably the most common, but there's a myriad of decorative fan grills that can be used as well.

Once you kill the fan noise, the noise created by the hard drive often becomes more noticeable. This is often where noise caused by vibration comes into play. Modern hard drives create quite a lot of vibration which can easily turn your case into a soundboard if no attempt is made to contain it. Using rubber grommets while mounting the drive can help prevent that. Also, as with the case fans, some drives create more noise than others, so a noisy drive can be replaced with a quieter one. Something to be on the look out for when looking for a quiet drive is if it uses fluid dynamic bearings. In general, drives that use fluid dynamic bearings will be quieter than drives that use conventional ball bearings. So far Seagate's Barracuda 7200.7 series are the quietest drives I've found(when I got mine I had a few worried moments of thinking I might have gotten a dud, since I didn't hear it spin up). There's not much you can do directly to the drive to quiet the noise created by the spindle motor that spins the drive platters, but you can help contain the noise(again) by insulating the inside of the case.

Insulating the case is often over-rated. Insulation can provide an overall reduction in noise levels, but it shouldn't be expected to make a huge difference. Just like water, sound will leak out though any little opening that isn't covered with an air tight seal, and in your average case there are plenty of those places(such as the openings for case fans). Furthermore, when a sound wave is absorbed by the insulation the sound energy is converted into low grade heat. For that reason it's possible that the interior of your case may be a bit hotter after you apply the insulation. If your case has adequate ventilation though, you shouldn't have to worry about this at all. Applying insulation to the inside panels of your case will also cause them to be heavier which will make it harder for them to start vibrating. Pax Mate(which can be familiar with a number of different sites) is probably the most popular insulation.

Another solution(my personal favorite ), is to forget air cooling entirely and build a watercooled machine. Watercooling allows you to ditch the processor heatsink completely and gives you more room to work while finding an acceptable balance between system temps and noise levels. Watercooling is more expensive though(unless you have the means to make your own parts), and does require more time to install in the system. However, in addition to getting rid of the heatsink, watercooling also allows you to use less or no case fans at all. Less airflow is needed in the case since the heat from the processor is contained in the water instead of being dumped into the air inside the case. General purpose watercooling components can be found at either Danger Den' ">http://www.dangerden.com or Swiftech' ">http://www.swiftnets.com/. Xice specializes in low noise watercooling. A review of an Xice kit can be found here, products can be found at the Flickerdown Store' ">http://shop.flickerdown.com/xice/).

If, by chance, you're a kindred spirit(meaning you aren't happy until you hear no noise from it at all), you'll probably have to build some kind of external enclosure to contain the offending components. Building such an enclosure can turn into an extremely expensive project, or can be relatively cheap, depending what materials you use. MDF(Medium Density Fiberboard) is a reasonably good building material to use since it's very dense(denser = better insulator), and is fairly inexpensive. The trick isn't so much in stopping the noise from getting out though, but in controlling the airflow such that a sufficient amount of air can get out, but all the noise stays in. As mentioned above, noise leaks are something to watch out for also. The best work of building an insulating wall can be easily compromised by not properly sealing around a small opening used for cabling or air ducting.

If you have any questions or have spotted any glaring mistakes in this guide, please feel free to PM me.

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Containment Breach

Do not meddle in the affairs of archers, for they are subtle and quick to anger.
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