By Michael McSherry
The Principle: Heat Transfer
Your computer has a few "hot spots" which generate more heat than the other components. Typically, these are the processor and power supply, although hard drives and extended video cards are also common culprits. In a closed computer case, you can imagine that the heat of a system builds rather quickly. Out with the hot, in with the cold; your computer needs to transfer heat away from the core components. Heat transfer, in this sense, refers to the conduction and convection processes which allow for the efficient heat exchange between your computer's internal components and the (hopefully) cooler surroundings. There are currently two main methods employed in dealing with computer heat: traditional fan cooling systems and higher end liquid cooling systems.
Traditional Fan Cooling
The same way you blow on your food when it is too hot, fan cooling systems work by running cooler air over the surface of a warmer object. As the air passes over the heated object, some of the energy contained therein is passed off to the atoms of the air through a process called convective heat loss. This is also the driving force behind wind chill. Fans have remained the most popular method of cooling computer systems as they are relatively inexpensive, easy to install, and easy to repair. Oftentimes, a fan system is supplemented further by a heat sink. Computer heat sinks are typically placed on the processor, where conductive heat transfer allows for the heat generated by the computer to be spread out over a much larger surface area. In this way, the effects of convective heat loss are more pronounced, as more cool air can pass over a larger surface.
Liquid cooling is much more efficient than traditional fan cooling, though its primary disadvantage is a higher cost. In terms of efficiency, consider how quickly water cools a hot pan versus leaving it sit at room temperature. Water has a much higher level of thermal conductivity, meaning it can exchange heat at a much higher rate (over 3,000 times as much!) than air. Liquid cooling allows for piping filled with water to be in direct contact with the heated computer component. The water is heated and transferred away from the component, where it circulates out to a radiator, which is in turn cooled by a fan. As you can see, liquid cooling still uses components of traditional cooling. For example, a 41R6039 heat sink in a traditional fan setup is analogous to the radiator and fan of a liquid cooling system. Hopefully this introduction to computer cooling has provided you with the foundational knowledge to understand the function your computer's fan or liquid cooling system serves.
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