Make Your Computer Quieter
Personal computers are once again on the march toward greater ubiquity; the "home-theater PC" (HTPC) trend is one example. HTPC builders have stumbled across another trend in the computing world, one that is much older: making computers quieter. There are entire websites that service this niche, and even entire companies. But really, the basic principles are fairly simple.
This is often one of the easiest, cheapest solutions to implement. Bigger fans can spin slower while moving the same volume of air (or spin at the same speed and move more air, as we will touch on below). This often means they make less noise, but it also means that they make lower-frequency noise. High-pitched noises (such as a fan that "whines") are more annoying to human beings. And after all, the goal is not to post a lower reading on a sound level meter; the goal is to be less noticeable.
Case fans are commonly 80 mm fans (they measure 80 mm x 80 mm, with a thickness somewhere around 15 mm). Many cases will accomodate 92 mm or 120 mm (or even larger) fans instead. 120 mm fans are the largest "normal" fans, although a handful of cases have begun incorporating enormous 250 mm fans into their case designs. If all your case can handle is 80 mm fans, your options are either to live with it (and try some of the tricks below), buy a new case, or pull out your Dremel and cut larger holes for bigger fans.
But case fans are not the worst offenders here. Even worse are the various little fans that come with various pieces of hardware. Chipset fans are almost always 40 mm, and can sometimes be the most annoying source of noise in a computer. As a special bonus, chipset fans are also often low-quality fans that fail relatively early. Close behind them in noise are video card fans, which are now often 40 mm blower fans. Processor heatsink/fan combinations are usually slightly better; they usually have a 60 mm fan. In all of these cases, the fan is normally mated to a purpose-built heatsink, which means replacing the fan involves buying a new heatsink as well (or getting creative with how you mount the fan). Third-party heatsink/fan combinations (and sometimes just big heatsinks; more on that later) are available for all of these.
This leaves one fan (for the way most computers are built, anyway) that we haven't mentioned; the power supply fan. There's basically no way to replace the fan in most power supplies with a bigger one, which means you need a new power supply if you want a bigger fan. This may not be a bad idea anyway (most buyers don't pay much attention to the quality of their power supply when they buy it, and quieter models are often higher-quality), but it is a relatively expensive fix. It also bears mentioning that for a power supply, a larger fan can lead to inferior cooling. 80 mm fans can be placed on the "back" of an ATX power supply, facing the outside of the case and allowing good "front to back" airflow through the power supply. 120 mm (and occasionally, 140 mm) fans have to be placed on the "bottom", which means they are essentially blowing air straight at the circuit board(s) in the power supply and hoping it flows out the back. Many use some sort of ducting to guide the path of the air, but this is only somewhat effective.
Even better than a large fan, is no fan. Eliminating fans entirely is a greater challenge, because it requires more careful design of the system as a whole. You can, for instance, buy a motherboard that is entirely fanless (passive cooling as opposed to active cooling with a fan) . But it was almost certainly designed under the assumption that some other fan in the system would provide some airflow across its heatsinks. If you don't have a fan somewhere else that can provide enough airflow, you can create problems.
First of all, take a good hard look at your case fans. Most "normal" ATX cases (as opposed to "upside down" cases with the power supply on the bottom) are built on the assumption that air will be drawn in at the front of the case, near the bottom, and exhausted at the back, near the top. Very often, one case fan at each of these locations (plus one on the power supply) is plenty. "Blowhole" fans on top of the case became somewhat popular a few years ago, but are not generally necessary. Side-panel fans, which are meant to target the processor specifically, are also not usually needed, and can make it harder to visualize the flow of air through the case. Really the point here is that having a huge number of fans is not necessarily worthwhile, even ignoring the noise. But having fewer fans may mean you need to be more careful to keep all of your components cool.
"Upside down" cases don't have the exact same airflow pattern, but the same reasoning (a few well-placed fans are better than lots of indicriminately-placed fans) applies.
Fanless motherboards are now readily available; they usually have very large heatsinks, and increasingly they make use of heatpipes as well. Fanless video cards have been available for years, but until recently these were always low-performance cards that simply didn't produce much heat. Now, there are gamer-ready cards available in fanless models (often with gigantic heatsinks). Similarly, while there are some low-power processors specifically sold for fanless operation, there are large heatsinks that can make passive cooling for some higher-power processors.
As you might imagine, there are some major caveats here. First, that very high-power components (very often, anything consider "top of the line") will still need active cooling. Second, that many fanless devices are designed on the assumption that some other fan, somewhere, will provide at least a little airflow to them. When you are trying to transfer heat from a solid object to air (which is the entire purpose of a heatink, and of nearly all PC cooling systems), convection is dramatically more effective than conduction. Having air just barely moving across the heatsink can make a considerably difference.
And third, you must be careful to avoid unintended consequences. For instance, every vaguely modern motherboard has voltage regulator modules (VRMs) placed near the processor. These devices regulate a 12 V DC supply down to the 1 V or so that a modern processor needs. In doing so, they create a fair amount of heat. Normally they are cooled by air that just happens to be moved by the processor's fan. If you eliminate that fan (or use one of the many third-party heatsinks that direct air in parallel to the motherboard, not down at it), you may have problems.
Not all fans are created equal. Some are built to move as much air as possible, others are built to be very quiet, and most try to strike a balance. The trick here is that getting the quietest fans possible is not necessarily wise; if you need 3 very quiet fans to circulate enough air, where 2 slightly louder (but slightly more powerful) fans would also suffice, you may be better off with the louder fans.
One of the major factors in determining how loud a fan is is the type of bearings used. There are two common types, and then a variety of less common types that are mostly just variants on those two basic types. Ball-bearing fans have ball bearings, with lubricated metal spheres between the "fixed" frame and the rotating hub and blades. Ball bearings are very reliable, but tend to be loud. And when they eventually fail, they will generally be very loud for a time, before seizing up completely.
Sleeve bearings are simpler. They essentially have two metal rings, one affixed to the frame and one to the hub, one inside the other. Lubricant is placed in the thin gap between them. Sleeve bearings are typically significantly quieter, but will generally fail sooner. Worse, they often fail completely silently; one day they just seize up. FrostyTech has a guide that discusses the tradeoffs between these two types of bearings.
In addition to these differences, there are subtle differences (such as blade design or quality of materials) that can make a substantive difference in how loud a fan is. For this reason, it is important to read up a little on a fan before making a purchase. At the very least, it is useful to have some idea of what companies typically produce quieter fans (such as Yate Loon or Scythe).
Slower-spinning fans will, all else being equal, normally be quieter. It really is as simple as that. But there are a few ways to slow down a fan, each with positives and negatives.
Virtually all motherboards now offer automatic temperature-based fan speed control. Normally this means that the motherboard will monitor the processor's temperature, and adjust the speed of the processor fan appropriately. But increasingly, many motherboards now have sensors to monitor the "ambient" air temperature (or at least, the temperature very close to some part of the monitor) and to then control one or more case fans.
Almost all video cards and many chipsets and video cards now do the same thing with their respective fans, with varying levels of success. So this can at least ensure that a computer sitting idle will be quieter. Some case fans also come with their own attached temperature sensor, and can therefore regulate their own speed.
You can also manually tweak fan speeds up and down, based on what you think is appropriate. There is now an entire market for fan controllers intended to make this convenient. A fan controller can be a way to reign in the noise of an otherwise-loud computer while it idles; they became popular as gamers began building increasingly loud systems, and wanted a quick-fix way to quiet them.
You can also just (semi-)permanently slow down a fan. One way is to simply place a resistor in series with the fan; some of the voltage delivered by the power supply will be dropped across the resistor, and the fan will "see" less of it. Nexus sells a line of fans that are nothing more than Yate Loon fans with such an inline resistor. This method is imprecise, because fans are not linear devices, but relatively easy and very cheap (resistors cost about $0.05).
Another solution to permanently slow down the fan is to rewire it. PC fans that are built to connect to a Molex power connector expect to see a 12 V input. Rewiring the fan's connector so that the fan is fed 5 V instead (connecting it to the red and black wires instead of yellow and black) will slow the fan down considerably, sometimes to the point it will not start without a push. Most people that use this trick will instead connect the fan to yellow and red, so that it sees a 7 V input. There is a small risk that the fan could possibly fail in a short-circuit state, thereby shorting the 12 V and 5 V rails together and, at best, causing the power supply to immediately shut down. But in general this works pretty well.
In most systems, taming fan noise is about 90% of the battle. But there are a few more areas to look at, if you want to eliminate as much noise as possible.
The first is your hard drive. As one of the few parts of a modern computer with moving parts (other than, of course, the fans), the hard drive can be a major source of noise. The most effective solution is simply to be sure you are buying reasonably quiet hard drives. Many reviews take note of hard drive noise; Silent PC Review provides plenty of data, and even audio recordings.
Even if you have a relatively loud hard drive, you can mitigate that by reducing the amount of vibration that it transfers to the case. A vibrating case can considerably amplify noise. The usual solution is to "soft mount" the drive; some cases provide special screws with rubber grommets for this purpose. Depending on case design, it is sometimes possible to improvise by sitting the drive on top of some soft material placed on the floor of the case (preferably two "rails" of some materials, so that air can move under the drive), or hanging it with string in a 5.25" bay. These of course are not good solutions if you tend to move your computer a lot.
Soft mounting is not just for hard drives. There are soft-mounting kits for fans, as well as silicone gaskets that can be placed between the fan and the case. A handful of processor heatsink/fan combos even soft mount the fan to the heatsink, or do something similar.
It is also true that a case made of heavier material will, all else being equal, be quieter. A thick steel case will be quieter (but heavier - and also cheaper) than an aluminum case. There are also various "sound proofing" products on the market, some of which are basically just a heavy foam meant to weigh down the case's side panels and some of which are a bit more clever.
The truly dedicated will also go after the other, less constant sources of computer noise. Loud CD/DVD drive? Hunt down a quieter one. IBM Model M keyboard? Replace it with a quieter dome-switch or scissor-switch keyboard, such as most any modern keyboard. Printer sounds like an enraged robot? Shop for something less annoying.
Unfortunately, trying to cut out noise in these areas often means significant tradeoffs in other areas. A quieter optical drive may well also be slower. A dome-switch keyboard will be far quieter than the Model M's buckling spring design, but will not have the same tactile response. The ultimate downside of trying to make your computer quieter is that you will have to deal with some tradeoffs, whether in performance, cost, or some other metric.
When quiet isn't quiet enough, there are some more extreme solutions available. But if you thought there were tradeoffs before, get ready for some even larger ones.
Water cooling works by transfering as much heat as possible into water (or if you wanted to go really exotic, some other working fluid), then pumping that water through a radiator to cool it. Water cooling will not result in a completely silent system; you will still need to move air across that radiator, and you have added a pump that will make some noise. But you have now eliminated the various little fans throughout the system, because there is no longer any need for separate fans on the chipset, processor, and video card, or to provide much airflow through the case.
Water cooling is normally fairly expensive, requires effort in the installation and maintenance, and carries some (ever-decreasing) risk of a leak spraying water all over your computer. The pump and the power supply for the pump do add some noise. So there are downsides. But done well it can make your computer quieter and cooler, which is why it has become fairly popular among overclockers.
Various companies have produced products that attempt to make water cooling simpler by being somewhat or very self-contained. If you are looking for an easier way to get your feet wet (no pun intended), these might be worth a look.
As we have seen, fans are a major source of computer noise. So why not get rid of them? Going completely fanless is difficult, but it is still possible.
The major problem with going fanless is that you can easily push your hardware to the limits of the temperature range that it can handle, as many Apple Power Mac G4 cube owners learned. You also may need some quite large heatsinks. So job one is finding components that don't demand a lot of power and, therefore, won't produce a great deal of heat.
That will almost always mean significant tradeoffs in performance. Right now, most fanless designs rely on a VIA C7 processor and a motherboard with integrated video. The two biggest heat sources in a computer are normally the processor and video card, and the C7 is a very low-power processor. Integrated video also uses very little power. But neither of these offers especially great performance.
Fanless systems also tend to rely on external, laptop-style power supplies rather than ordinary ATX power supplies. These external power supplies normally supply just one DC voltage, which the motherboard (or some other piece of hardware) regulates down to the other voltages that the system needs. The reasoning is two-fold. First, most ATX supplies are simply not build for fanless operation, whereas these external supplies are. In large part that is because most ATX supplies expect to be supplying a 200 W load, not a 50 W load. Second, the power supply will never be 100% efficient, and it will therefore produce heat. Moving that heat away from other components makes it easier to keep everything cool.
Once you've cut out all the fans, there really aren't many moving parts left. How many you can cut out depends on just how devoted you are to the idea of a computer with no moving parts.
In general, "no moving parts" is taken to mean no fans, and no hard drive. Not long ago, getting rid of the hard drive meant buying a Compact Flash card and an adapter, and living with poor sustained transfer rates and (if you are performing a lot of file operations) a short life for the Compact Flash card, not to mention severely limited drive capacity. Now there are (pricey) solid state drives that alleviate some of these concerns, but are still quite expensive.
If all you've dealt with is the hard drive and fans, it is of course somewhat misleading to say you have built a machine with no moving parts. It is hard to get by without an optical drive of some description, or a keyboard or mouse. The mouse could potentially be replaced with some sort of touchpad device (although finding a way to right-click may be a challenge), the keyboard with an uncomfortable laser-projection keyboard, and the optical drive with... an optical drive installed on some other computer on the same network. But these all require major tradeoffs for very little gain. Most people building "no moving parts" systems ignore these peripherals, rather than deal with such unpleasant tradeoffs.
Better to start off by dealing with your fans instead.