Hard disks

Today, it's possible to buy or build a PC without fans but you still can't have one without a hard disk. And hard disks, with all their moving (often constantly) parts, are usually noisy. Desktop 7200rpm drives are now commonplace, and newer desktop hard disks even run at 10,000rpm. Fortunately, these advances in hard disk speeds have been accompanied by new technologies to limit the noise the disks generate. Most hard disk manufacturers now either offer a range of quiet disks or use special quietening techniques. If you've got an older hard disk, here are some products that may help.

Hard disk mounts These are L-shaped metal blocks with rubber in between. Hard disks typically have four contact points with the case, at the four holding screws. If you have a spare 5.25in bay, you can use these mounts and move the hard disk to the larger bay. At each corner of the disk you'll have one mount screwed on to the hard disk and one on to the bay ensuring that the metal from the hard disk doesn't touch the metal on the bay and therefore doesn't transmit vibrations to the case.

Hard disk heat sinks These serve two purposes: they have four rubber rings that act like mounts to prevent the hard disk coming into direct contact with the case, and they have a heat sink consisting of a collection of copper pipes that dissipate heat from the higher spindle speeds drives.

Enclosures Some manufacturers sell complete enclosures for hard disks. An enclosure will typically fit in a 5.25in bay and completely contain the drive, sealing in vibration and noise. But check that they are rated to handle the spin speed of your hard disk and are capable of getting rid of the heat the hard disk generates. Some enclosures dissipate heat using one or two little fans. As with any fans they generate some noise themselves so you'll have to balance that against the how far the enclosure quietens the disk overall.

Power supplies

In many PCs this is the component that generates the most noise. When choosing a PSU for your PC shopping around can save you a lot of sound. Manufacturers of quality PSUs normally have a noise rating listed along with the technical specs. And if you don't need a 550W power supply, don't buy one. It will probably make the same amount of noise even if you are only pulling 200W out of it. If your budget stretches to it there are some PSUs now available that are completely fan-less. These tend to come as standard on very expensive cases that are marketed as quiet cases, but some of them are also available for purchase to fit in any standard PC. They dissipate heat via a large radiator type heat sink that sits outside the PSU and outside the PC. Some of the heat sinks stick out a few inches behind the computer.

Graphics card heat pipes

Performance graphics cards generate a lot of heat. In fact the processors on today's high end graphics cards have more power than the main CPU in any PC you've had for a few years. Because of the international standardisation on size and location of PCI and AGP cards the graphics card fan has to be fairly small. This means that it needs to spin faster to keep the card cool. Some cards have high performance RAM on their flip side and sometimes these need active cooling too. The best route to take with graphics cards is to settle for a lower tech option if you don't need the power. But if you'd still like to lower or even remove the sound from the graphics card's fan you'll have to get a VGA heat pipe. To fit it you'll have to remove the heat sink and fan from your graphics card, voiding the manufacturer's warranty on the card. The heat pipe spreads the heat over a much wider surface area and provided you have sufficient airflow over the card you may get away with not having a fan to cool your graphics card down.

Other products

Thermal paste This is a vital product in any PC builder's kit. It's normally applied between a processor and the heat sink and helps conduct the heat away from the chip. Remember, too much paste is counter-productive - you need only a thin film.

Chassis fans The most popular size of chassis fan is the 80mm. However, 120 mm fans are now becoming quite popular because they tend to generate less noise. Not all 120 fans may fit your case, however, but there may be adaptors available that will allow you to use a 120mm fan in a location normally reserved for an 80mm unit. Some of these chassis fans are quite clever - they come with ducting that leads to the CPU to provide a more direct route for CPU heat to leave the case.

In quality cases you will normally have at least one or two chassis fans at the front of the case drawing cool air in. Often this air is dragged in over a dust filter which can cause a little noise. In our opinion it's not worth removing an intake filter to reduce sound. The filter serves too important a purpose. Removing a filter may well save you a little noise, but the extra dust going into your PC and settling on fan bearings will more than negate that benefit.

Chassis fans range from about 15dba to about 30dba. Quality case manufacturers who provide chassis fans tend to provide fans that generate less than 20dba.

Regulators Most electronic shops will stock a variety of devices that can control fan speeds. It's possible to have all the fans in your PC, from your PSU to the CPU to the chassis fan running only at the lowest rpm they need to run to keep the relevant parts within your pre-defined operating temperature range. Automatic adjustments fan power can make it spin faster or slower and these automatic adjustments can be based on the output readings from temperature sensors. These are all products for the professional or the very keen enthusiasts. Attempting to fit them yourself may result in some burnt out components before you get fully familiar with them and fully competent at setting them up.

The future

The quest for maximum performance invariably results in hotter components that require more and more cooling. Whether that's done with fans or water pumps, it increases the noise generated. The good news is that boffins at chip manufacturers are constantly looking at new ways of designing chips to consume less power and generate less heat.

There are a lot of interesting ideas and concepts being tested. One of them involves 'nano-lightning' - the production of an air flow along the surface of the heat sink by ionising and pumping air molecules using minute electric currents. Electrodes containing carbon nanotubes have a tiny charge applied to them resulting in electrons being knocked off air molecules and the consequent positively charged ions being attracted towards a negatively charged electrode, taking heat with them. This flow of ions is controlled to move the heat away from the surface of the CPU. Viola, no fans. But this, and other innovations, are still in the testing stage and have a long way to go before reaching the market.

Researchers will eventually develop systems for transferring heat out of PCs without using any noisy equipment like fans and pumps. In fact, here's hoping they develop ways of increasing PC speed using techniques that don't involve the creation of heat in the first place. That, together with advances in solid state technologies involving storage devices with no moving parts, should make for some pretty silent computing in the future.