Cases
Having all these quiet components is no good if you have a flimsy case which rattles and resonates, or allows little airflow forcing you to push your fans harder. Much is said of aluminiums cooling properties when used for cases. Personally I prefer to use coolers for cooling and stick to my case being for holding it all together. Aluminium makes a poor choice for a quiet case due to it's being light, so allows more sound through and vibrates more easily, and also aluminium cases are usually thinner than steel cases worsening alumiums suitability. So all but one case resomended here is made from steel.
The case that isn't made from steel, is ironically the best choice for a “silent” system. The TNN 500AF is Zalmans answer to the specialist market, for those who want a system with no active cooling and so no noise from air flow. This is incredibally expensive, you could build a top of the range system for the price of this case alone. But you will find nothing that cools to this level at this volume. This case basically works as one huge heatsink, being made from 5-7mm thick aluminium it's incredibally heavy and designed for workstations and servers used in environmnents where noise it not an option. Heat is transferred to the case material through use of heatpipes and cool the cpu and gpu. The
psu is of the fanless variety with a high efficiency of 78%, not world leading but due to the impressive cooling not as much an issue as using a fanless
psu in a regular system. It also comes with heatpipe coolers for the hardrives to help cope with the lack of airflow.
http://www.zalmanusa.com/usa/product...dx=64&code=020
The most popular manufacturer for quiet cases is probably Antec. Their low prices are the main reasons for this, but this doesn't detract from the quality of their cases.
The two best choices are the Antec SLK3700BQE and Antec SLK3000B, the SLK3700BQE comes with a 350W
PSU which isn't perfect for quiet situations and much better are available. These two items are good value, and if your fond of using a dremmel then these cases make excellent projects.
http://www.antec.com/uk/productDetails.php?ProdID=00300 SLK3000B
http://www.antec.com/uk/productDetails.php?ProdID=00363 SLK3700BQE
If your willing to spend a little more on your case then the best solution comes from the company usually associated with HTPC cases Silverstone with their Temjin TJ06 PC case.
The unique thing about this case is it's take on airflow. Standard cases have a single path which air follows through the case, from the front of the case, past the hard drives, up to the cpu and out via the exhaust and
psu. This method takes a lot of force because of it's none linear path, and also picks up a lot of heat before reaching the hottest components. BTX is a new design aiming at changing this by using a wind tunnel across the cpu and video card but needs a completely new case, motherboard and
psu. Borrowing from BTX, the TJ06 uses a wind tunnel solely to cool the cpu, northbridge and ram and also positions the motherboard upside down to keep the cpu and
psu away from one another. Using this method it's possible to even cool the cpu passively, and Silverstone offer a cooler recommended for use in this setup.
http://www.silverstonetek.com/products-nt01.htm
This wind tunnel style cooling is likely to become quite popular for quiet systems. Antec's soon to be released P180 uses a similar method, though rather than cooling the cpu this way, it has moved the
psu to the bottom of the case and given it it's own wind tunnel, something that may prove very effective since something most people struggle with when making a system quiet is preventing
psu's from increasing their fan speeds.
http://www.silverstonetek.com/products-tj06.htm
If your system is going to be used just for media purposes, and likely to be stored underneath a television, you aren't going to want a standard tower pc case.
Silverstone are one of the better known makers of cases suitable for this, and the best being the SST-LC01 HTPC Case. Keeping things quiet in such setups is more of a challenge than if you have the freedom of a full tower setup. So more consideration has to be given in the choice of components, lower power components will make keeping it cooled quietly much easier. If the pc is basically just going to be a media centre this doesn't make the use of such components a problem. A 3ghz+ cpu just isn't needed, especially when the main tasks will be video based, something most modern video processors help a lot with, and so the slower the better, less than 2ghz being ideal, and also the video card won't need fancy 3d functions, and so the lower end ATI and nvidia products with passive cooling will suffice.
http://www.silverstonetek.com/products-lc01.htm
If you are going to be putting a mini-itx system together your task of keeping things quiet is much more simple. The Scythe e-Otonashi fanless EPIA-M cooling case is ideal for an EPIA based media box. Being fanless the only source of noise (excluding electrical buzz) will be from the hard rive and/or optical drive, and so using a quiet, low rpm notebook drive you could build a system that would be all but inaudible from 1m+ away.
http://www.silentpcreview.com/article143-page1.html Dampening
The last stage of getting your pc quiet, you've replaced every fan, turned down the voltage, undervolted your cpu, replaced your video cooler, de-coupled your quiet hardrives, and put it all in a steel, quiet case. but theres still that slight hum and whine that you just can't get away from. Every individual component is very quiet, but that slight noise of each added together is just noticable. This is where case dampening comes in. On it's own it won't sound proof your computer, but if you are at the stage where it's already very quiet it can do enough to cut out that last amount of noise.
I'm only going to recomend one product here. The materials used are quite expensive, even the budget products are $20. But to be truly effective for me it's all or nothing, if you are going to take to time and money to dampen your case it's worth going the whole hog.
Acousti Products have a variety of differant Acousti Packs, some precut for specific cases. Their top of the line product is the AcoustiPack™ Deluxe (v2).
This stuff is surprisingly heavy, it looks like foam, but this pack weighs 3kg
http://www.acoustiproducts.com/en/acoustipack.asp
If you are on a budget you could consider rubber carpetting. This site here has some information on it.
http://www.7volts.com/quieter.htm