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Cooling Theory Made Easy

How To: Properly Plan And Pick Parts For An Air-Cooled PC, Part 1

Energy Conservation

We don't want to bore you, but it is important to emphasize what a large undertaking the right cooling system can be. PCs are among the most inefficient appliances of all time, because much of the electrical power they use is converted directly into heat (energy). There's no getting around it; you just have to live with that reality.

Even a simple 40-watt light bulb emits enough heat to melt plastic and trigger a fire. PCs use 60 watts or more at idle. Under load, that number can quickly jump tenfold or more! Bear this mind. It'll frame our conversation and help you respect what a tough task PC cooling really is.

Heat must be dissipated, enough so that the PC’s components don't exceed a certain maximum temperature. The task is achieved in several stages:

Dissipation from the surface of the heat-producing component (be that a CPU, GPU, or motherboard voltage regulator)
Absorption in the heat sink and transport to the cooling fins
Emission of heat to the air (which, unfortunately, conducts heat poorly)
Evacuation of the hot air from the enclosure

In steps one through three, we use commercial heat sinks with fans, which are designed to fit as many interfaces as possible and can sometimes cause installation issues on more elaborate or specialized platforms. Fortunately, most of those issues are easy enough to solve. That last step, however, requires advanced planning, so we'll start by taking a look at airflow.

This is directly related, of course, to the placement of the components within your enclosure. So, on the next page, we'll start by taking a look at the basics of power supply construction, cooler direction, and case fans.

Stack Effect:

Hot air rises, while cold air sinks. So, the upper part of the housing is normally the warmest. We have to keep this basic principle of physics in mind when planning a cooling system.

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