Anybody who has been near their share of computer systems will appreciate that not all systems make the same amount of noise. There are a number of reasons for why this is so. Firstly, a computer makes noise for different reasons. Generally, anything mechanical is going to make noise. So, in a PC, that's the hard drive(s), optical drive(s) and fans. In general, however, fans make the most noise, and so a quiet cooling solution is the easiest way to make the entire PC much quieter.
Some PCs don't need quiet cooling. A server, in a room full of other servers, which have fast, noisy hard drives and a hefty air conditioning unit, wants the best possible cooling without costing a bomb, and there's no need for it to be quiet. At the other end of the scale, a computer in a recording studio might want to be extraordinarily quiet. To achieve this, the PC case might even be moved into a separate room.
Of course, most people reading this just want their home or office PC to make less noise. Readers interested in building a quiet PC for their living room might also want to pay attention to this HEXUS.help guide.
So, we've already established that the most effective means of making a PC quieter is to concentrate on the cooling. The best time to consider this is before you even buy components. Think about the case; think about the purpose; think about the demands; and then find a cooling solution that works effectively, but quietly.
Before you get alarmed and think we're about to suggest you dive into water-cooling or something more sinister, be assured that this is not the case. Such cooling solutions are in most (but not all) situations, excessive. Certainly for fairly general usage, careful choice of 'air cooling' solutions will be sufficient. Here are a number of aspects to consider:
The heat sink is usually the noisiest part of the PC. More specifically, the fan on the heat sink is. The CPU need good cooling to operate error free. An aluminium or copper block draws heat away from the CPU, into fins, which then dissipate that heat into the air, with the help of a fan. The problem is, these fans can be noisy.
If you don't care about noise, then this really isn't a big deal, as long as the cooler keeps your CPU cool enough. However, when noise is an issue, it's important to be a bit more picky. The first thing to look for in a CPU cooler is how big the fan is. A larger fan will generally be able to move the same amount of air as a smaller fan, but without spinning as fast. This results in less noise.
A 5000rpm is probably going to be quite noisy. A 2000-3000rpm fan will be better. Even lower is fantastic. Of course, all the time, check the specs of the cooler to make sure it can cope with your CPU.
The fan itself might not need to spin as fast if the rest of the heat sink is designed better. Different materials and designs dissipate heat more effectively. A heat sink with thinner fins, but more of them, has a bigger surface area with which to shift heat. As a result it can have a quieter fan.
More elaborate coolers use heat pipes. These draw heat away from the source very quickly, to another location where the heat can then be dissipated into the air. While more expensive, these solutions can often be quieter (but not always.)
Always check for a decibel (dB) rating on a cooling component. Ideally it should state how far away the instrumentation was when the reading was taken (your PC will sound silent if you try to listen to it from 100 metres away.) 40dB is certainly noticeable, 30dB less so, particularly if there are other noise sources in the room. Even less is great, but take such ratings with a pinch of salt.
Power supplies, just like CPUs, need good cooling. It's imperative that they keep cool, or else they won't provide stable power... or even blow up. That doesn't mean they need to sound like a wind tunnel, however.
A well designed PSU will maybe use one large fan, or two well placed fans, to cool nice big internal heat sinks. Three fans might look good on paper, but this might not necessarily mean they're quiet; they might be compensating for bad internal design.
Be careful with PSU choice. Cheap PSUs are, in our experience, not reliable if you expect the full stated load of them. A cheap and silent PSU seems even more troubling. Make sure you buy a PSU that is of a quality to meet your power demands while not making too much racket.
Believe it or not, graphics cards can be noisy. This is especially true for higher-end models. Luckily, they're often temperature controlled (more on that shortly.) However, if they're always going to be hot (say, you play games a lot) then it doesn't really matter, does it? Graphics cards with special cooling solutions can cost a little more, but they need not cost the earth.
You can buy third party cooling solutions for your graphics card if you want to keep the one you have. They can be easy or hard to install – it depends on what you buy. Read up on things like compatibility and installation instructions before making a purchase.
In general, any fans supplied with a case are going to be cheap. We're talking very cheap here, and so chances are they're going to be noisy. Some cases do have decent fans, however, so don't write them off until you've actually heard them.
If it turns out that they're a bit noisy for your liking, replace them. It's a good idea to buy a case that has mounts for large (120mm) fans, but even 80mm fans can be quiet, if you buy the right ones.
Fans don't need to be running at full speed all of the time. When the system isn't fully loaded, it's not putting out as much heat. Manufacturer's know this, and so some devices, such as PSUs, graphics cards, motherboards, etc, have temperature controlled fans, or fan power connectors.
You can add temperature controlled fan support by buying a fan controller designs for such a purpose. Some are more advanced than others, with digital settings and customisable thresholds. However, it that seems a bit too costly, consider the 'fanbus'. These essentially give you manual control over a fan's speed. A fanbus usually supports three or more fans, depending on what you buy. They might be integrated into another device, like an 'all-in-one' front panel, or they might just be a front panel insert with a few knobs on the front. These are great, providing you know when fans need to be turned up a little.
Fan controllers can work in more than one way. Some change the voltage to the fan. This is similar to what you can do yourself by rearranging the fan's power connector (something this article doesn't go into). The problem with this is that some fans don't like lower voltages and won't spin very well.
Another method is called pulse width modulation (PWM). This is generally more common these days. PWM provides full voltage to the fan, but only for a certain percentage of a cycle. A 50% duty cycle means that 50% of the time the fan gets 12 volts, but the other 50% of the time it gets 0 volts. The speed of the fan is controlled by adjusting the duty cycle. Depending on the PWM implementation, this can work well, but fans with lights in them might flicker.
Fan controllers are often rated to a certain power. Any wattage above that could burn them out. Usually, fans don't draw enough current for this to be a problem, however.
Companies are always looking to trump one another. Don't expect the best looking cooler to do the best cooling job. Sometimes the quality is only skin-deep. Check for reviews to see how well a product performs and how noisy it is.
There are some great innovations out there, like use of heat pipes, or clever orientations of coolers, or fan designs. Thermal loads don't seem to be getting much lighter, and so companies need to keep finding new, better cooling methods. This keeps the market quite fresh and competitive, which is good for the buyer.
If performance and silence are key, make sure you're buying a product that gets good reviews from reputable sites online and seek the advice of forums too. With so much choice, a little research will go a long way.
There are innumerable player in the cooling market. Some make cases, some make heat sinks, some make fans and so on. A few big names are worth mentioning, however.
Enermax, Silverstone, Lian Li, Hoojum, Chieftec, all make cases which serve different purposes. For example, many of Silverstone's products are geared towards home theater usage, while Hoojum make small form factor cases.
Akasa are quite well known for their cooling products, as are Zalman (who specialise in quiet cooling) and Swiftech. There's often a lot of crossover between case manufacturers and heat sink manufacturers. In general, a company's heat sinks are as good a quality as their cases. There are some companies who don't build cases, however, like Gigabyte (better known for motherboards and graphics cards) who still make decent heat sinks.
As for fans, Akasa are once again a player. The quietest of the quiet tend to be made by Panasonic under the 'Panaflow' name. Other names include YS-Tech, Delta (more commonly associated with screamingly loud fans, but they also make quiet ones), Thermaltake and many more.