Just as the engine of your car needs to be cooled to prevent damage, so does the engine of your computer. Fast spinning hard drives and fast microprocessors inside small enclosures can lead to dangerous overheating and potential equipment damage if not addressed properly.

The common use of CPU cooling devices coincided with the release of fast 486-class PCs. CPU cooling devices have since evolved from being a practical computing accessory to an essential device for competitive equipment design. As computing devices get faster, the number of small heat-producing transistors grows ever larger. Transferring this heat away from sensitive areas and out of your computer requires the use of specially designed computer fans and coolers. Popular types of computer cooling devices include hard drive fans, CPU fans, and computer case fans.

Basic Components of Computer Cooling
Currently, CPU cooling devices include one or more of the following components: a fan, a heatsink, and/or a Peltier element. Each component can be independently used, but they are used in combination to provide enhanced cooling capabilities. The combination to be used is determined primarily by the type of cooling application.

Small hot surfaces generally require a heatsink to maximize the physical cooling area, and a fan is usually used to force air through the heatsink's fins. Computer cases and equipment enclosures often use a single fan or group of fans to exhaust hot air. Only extremely hot devices, such as overclocked CPUs and overclocked video cards, may demand the active cooling capabilities provided by a Peltier element.

Fans
Physical size, type of support bearings, fan speed, and propeller blade design define a cooling fan's performance and a overall CFM (cubic feet per minute) rating. Generally, higher CFM values are desirable since greater volumetric airflow results in better heat convection. Ball bearings provide quieter fan operation and an extended longevity when compared to their less-expensive sleeve-bearing counterparts.

Heatsinks
A heatsink's efficiency depends on the its thermal conductivity (a measure of heat transfer capability through a material) and the size of the exposed surface areas (with larger surface areas providing better heat dissipation). The thermal conductivity in metals is directly related to electrical conductivity, as both rely on electrons to transfer energy. Most heatsinks are constructed of aluminum - an inexpensive light metal that readily conducts heat. However, material research has shown that copper and copper-based alloys provide improved thermal conductivity (although at a significantly higher cost).

Peltier Elements
A recent innovation in computer cooling is Peltier cooling technology. Peltier coolers are active devices that operate somewhat like household refrigerators. Peltier elements are composed of different layers of composite ceramic-type materials. When an electrical current is passed through a Peltier junction, a thermoelectric cooling action known as the "Peltier effect" will result, with one side of the element becoming very cold and the opposite side becoming very hot. The cold side comes into contact with the device to be cooled (usually a high-speed CPU processor), and heat is removed from the other side by using a fan and heatsink unit.

Although Peltier cooling is well-known staple in the world of "overclocking" (where computer hobbyists try everything to extract maximum performance from their CPUs and Video Cards), they are not recommended for computers that operate under normal, non-overclocked conditions. The main problem with Peltier CPU coolers is that they thermally insulate the CPU so well, that in the event of fan failure, the Peltier element actually contributes to the accelerated overheating of the CPU. As well, water condensation can appear on the cold side of a Peltier cooling system, which can easily damage delicate circuitry and cause destructive electrical short circuits.