To ensure reliable operation and longivity of the computer components, it is neccessary to keep the chips, most notably the processor, cool. Overheating of silicon components will lead to electromigration that can lead to permanent physical damage.

This section should be especially of interest for people who are overclockering their systems because they run their components at above the recommended operating temperatures.

I must admit that the Kyrotech Vapourphase refridgeration is the most efficient cooling technique, but sad to say, it is also the most efficient at cleaning one's pocket out. So, without further ado, explained here are some rather basic methods of keeping one's computer cool.

1. Power supply fan

Every computer, with the exception of most laptops, has a fan integrated into the power supply. In normal baby AT formats, this fan causes some air circulation inside the casing, but isn't directed specifically at any component. The ATX form factor positions the power supply fan near the processor which provides a steady air flow directed at the processor. As a result, certain ATX designs don't really require the processor itself to have a fan; just a heat sink.

2. CPU heatsink with fan

Ever since the 486DX2/66, it has become standard fare to have a heatsink mounted directly on top of the CPU. The large surface area of the heat sink's fins enables increased heat dissapation. However, without any air flow passing through the heatsink, a stationary layer of air molecules stick to the surface of the heatsink due to surface tension. Rate of heat transfer is proportional to the temperature gradient between the hot heatsink and the cooler air; and as the stationary layer of air heats up, the temperature gradient is reduced, resulting in less heat flow. To prevent this from happening a small fan is mounted directly onto the heat sink to ensure a steady air flow through the heat sink. Not all fans are made equal however. Depending on the angle at which the blades are positioned and the angular velocity, the air flow created by similar sized fans can vary greatly.

3. Thermal compound

If the heatsink is not perfectly flat and in contact with a perfectly flat CPU, small pockets of air which act as insulation are trapped inbetween them. Since it is impossible to have a perfectly flat surface (surface finish is never perfect), thermal compounds with a high thermal conductivity are used to bond the heatsink to the CPU. These compounds are like a "glue" that solidify after application. When used excessively, the compund will form another barrier for the heat built up to cross, so care should be taken not to use thermal compounds in excessive quantities.

4. Peltier junction

Peltiers work on the same principle that thermocouples do. When two different alloys are bonded together, and one is at a different temperature than the other, an electromotive force is setup. The peltier cooler works on this principle, but in reverse. 2 alloys are bonded together and a voltage is applied across them. This forces the kinetic energy of the molecules be transfered from one alloy to the other, and hence sets up a hot end and a cold end. The cold end of course faces the processor and the hot end upwards where a fan will generate a flow of air to take the heat energy away.

5. Secondary fan

Secondary fans come in the form of expansion cards that fit nicely into ISA sockets. On each card is mounted either single or dual fan units. The main use of this card is to create an air flow in the area of the card peripherals. Those overclocking the 3D/Fx Voodoo based Monster 3D would do well to have this type of fan (Voodoo chip runs very hot when overclocked). However, take note that adding extra fans does not cool the computer (it only moves the already hot air around) unless there is a means of exhaust for the hot air. Without the means of exhausting the hot air, the extra fans are only compounding the problem by disrupting the natural circulation of air inside the casing.

6. Hardisk fans

There are certain hardisk fans avaliable that are essentially a casing with a fan mounted on it. The fan will protrude outside of the casing to suck in an intake of cool air. Useful for 7,200rpm and 10,000rpm SCSI hardisks like the Seagate Cheetah. Recently, some hardware reviewers even noticed that they could get higher and more consistant Winbench scores when they used a hardisk fan with a 7,200rpm Seagate Medalist Pro.

7. Remove all the metal plates covering the expansion slots at the back of the computer.

A reasonably good method only if there is a fan positioned inside the casing to force the air out. Particularly effective when used together with secondary fans in a large tower casing. Not much dust can get in.

8. Water cooling

Intel used this method to keep their proto-type Pentium 2 400MHz processor cool during an computer exhibition. That was when the Pentium 2 was just released and still built by a 0.35 micron die process. Some innovative overclockers have found ways of squeezing thin walled hollow tubes inbetween the fins of heatsinks. Running water through the tubes then made it "water cooled". However, it is not such a good idea unless you know what you're doing. First, you have to find a material of high thermal conductivity for the tubes. Second, the material has to be stable at high temperatures (wouldn't want the water to come out would you?). Third, a pump has to be fashioned to keep the water flowing and fourth, it reduces the surface area of the heatsinks that is open to air flow, so the usual fan is not of much use anymore.

9. Leave the casing open

This sounds very simple and straight forward so I don't need to explain it. Although there are people who swear by this, it is NOT recommended at all. First of all, dust will start to settle on the components and can clog up the CPU fan. Secondly, the casing sets up a convenction current inside the computer due to the different densities of air (because of different temperatures) inside it. This movement of the air will blow over the chips, cooling it by means of convection. Once the cover is removed however, the airflow is disrupted and there is no circulatory system anymore. A stationary layer of air molecules will then stick to the chips due to surface tension and act as an insulator, thus compounding the problem.