Air cooling
From TPU Reference
Air cooling is the most common (and cheapest) method of removing heat from critical heat sources within a computer, such as the CPU, GPU, and core logic.
A generic air cooling system has two critical parts: the heatsink and the fan. Heatsinks use various methods to absorb heat from a very small heat source, such as a CPU, and dissipate it out to some larger surface area where it can be absorbed by the surrounding air. Typically, this air is pushed (or pulled) by one or more fans, which permits cooler temperatures by replacing already-heated air with cooler outside air.
The general range of Heatsink/fan covers a lot of territory, both in price and quality. Heatsink and fan combinations are often included free of cost with products containing logic although after-market systems can be priced upwards of $90. Many characteristics determine which solution is best for a given situation, beyond just price and lab performance, like sound characteristics such as pitch, loudness and size in the case.
All air cooling can be categorized as either active or passive.
Active
Active air cooling spreads heat over a large surface area in a manner similar to passive cooling. Unlike a passive system, active air cooling uses a fan or turbine to accelerate air over the fin assembly. The increased number of molecules making contact with the heatsink combined with turbulence induced by the fan vastly increases the cooling performance. Thus, actively cooled heatsinks can be smaller.
Passive
Passive air cooling systems increase the surface area of the component so heat can be wicked away without fans or coolant. A passive cooling system usually consists of one or more heatpipes, which draw the heat from the heat source (CPU, GPU, Northbridge etc.) to a large area of fins. A passive air cooling system can be positioned in a manner that exploits natural convection currents or pressure differences to remove heat from the fin array. Semi-passive solutions situate the heatsink near another component's fan to efficiently recycle the fan's exhaust. Passive air cooling systems are the simplest of all cooling solutions, requiring no noisy mechanical parts or energy input. However, air has a low specific heat and is an acceptor of heat, reducing the effectiveness of passive systems.
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