Air Cooling

This air cooling article covers the many ways that potentially damaging heat is relieved from electronic computers.

A computer system unit's many components produce large amounts of heat during operation, including, but not limited to CPU, chipset, graphics card, and hard drives. This heat must be dissipated in order to keep these components within their safe operating temperatures, and both manufacturing methods and additional parts are used to keep the heat at a safe level. Air cooling is done mainly using heat sinks (to increase the surface area which dissipates heat), fans (to speed up the exchange of air heated by the computer parts for cooler ambient air) and in some cases (usually CPUs) using "softcoolers".

Overheated parts have a shorter life and may give sporadic problems resulting in system freezes or crashes.

Causes Of Heat Build Up

The amount of heat generated by an integrated circuit (e.g. a CPU or GPU), the prime cause of heat build up in modern computers, is a function of the efficiency of its design, the technology used in its construction and the frequency and voltage at which it operates.

After several years of use, the dust on a laptop CPU cooler makes the computer unusable due to rapid overheating.

In operation the temperature levels of a computer's parts will rise until the temperature gradient between the computer parts and their surroundings is such that the heat flow matches the input and the temperature of the computer part reaches equilibrium.

For reliable operation, the equilibrium temperature must be sufficiently low for the structure of the computer's circuits to survive.

Additionally, the normal operation of air cooling methods can be hindered by other causes, such as:

• Dust acting as a thermal insulator and impeding airflow, thereby reducing heat sink and fan performance.
• Poor airflow (including turbulence) due to friction caused by a turbulent flow that reduces the amount of air flowing through a case, possibly causing stable whirlpools of hot air in certain areas. This could also be caused by a poorly designed computer case.

Damage Prevention

It is common practice to include thermal sensors in the design of certain computer parts, for example: CPUs and GPUs, along with internal logic that shuts down the computer if reasonable bounds are exceeded. It is unwise to rely on this, however, as it is not universally implemented, and even if implemented is intended as a damage limitation feature and may not prevent temperatures from reaching dangerous levels such that repeated incidents will cause premature failure of the integrated circuit.

The design of an integrated circuit may also incorporate features to shut down parts of the circuit when it is idling, or to scale back the clock speed under low workloads or high temperatures, with the goal of reducing both power use and heat generation.

Air cooling

While any method used to move air around or to computer enclosures would count as air cooling, fans are by far the most commonly used implement for accomplishing that task. The term computer fan usually refers to fans attached to computer enclosures, but may also be intended to signify any other computer fan, such as a CPU fan, GPU fan, a chipset fan, PSU fan, HDD fan, or PCI slot fans. Common fan sizes include 60, 80, 92 and 120mm.

Air Cooling In Desktops

Desktop computers typically use one or more fans for heat management through air cooloing. Almost all desktop power supplies have at least one fan to exhaust air from the case. Most manufacturers recommend bringing cool, fresh air in at the bottom front of the case, and exhausting warm air from the top rear.

If there is more air being forced into the system than being pumped out (due to an imbalance in the number of fans), this is referred to as a "positive" airflow, as the pressure inside the unit would be higher than outside. A balanced or neutral airflow is the most efficient, although a slightly positive airflow results in less dust build up if dust filters are used.

Air Cooling In High Density Computing

Data centers typically contain many racks of flat servers. Air is drawn in at the front of the rack and exhausted at the rear. Because data centers typically contain such large amounts of computers and other power-consuming devices, they risk overheating of the various components if no air cooling measures are taken. Thus, extensive HVAC systems are used. Often a raised floor is used so the area under the floor may be used as a large plenum for cooled air and power cabling.