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Processor Cooling

Keeping the CPU cool is critical. Both Intel and AMD have technologies that reduce processor energy consumption (and heat) by turning off unused parts of the processor or slowing down the processor when it starts to overheat. But these measures alone are not enough. Today’s systems use one or more of the methods listed in Table 3.6. Figure 3.18 shows a heat sink and a fan.

TABLE 3.6 Processor cooling methods



heat sink

A block of metal (usually aluminum or copper), metal bars, or metal fins that attach to the top of the processor or other motherboard components. Heat from the processor is transferred to the heat sink and then blown away by the air flow throughout the computer case.


Fans can be attached to the processor, beside the processor, and in the case.

thermal paste or thermal pad

Thermal paste, compound, or grease is applied to the top of the processor before a heat sink is attached. Some heat sinks and fans come pre-applied. A thermal pad provides uniform heat dispersion and lies between the processor and the heat sink.

liquid cooling

Liquid is circulated through the system, including through a heat sink that is mounted on the CPU. Heat from the processor is transferred to the cooler liquid. The now-hot liquid is transported to the back of the system, converted to heat, and released outside the case. CPU temperature remains constant, no matter the usage. Some systems require the liquid to be periodically refilled.

phase-change cooling (vapor cooling)

Expensive option that uses a technique similar to a refrigerator: A gas is converted to a liquid that is converted back to gas.

heat pipe

A metal tube used to transfer heat away from an electronic component.

passive cooling

Passive cooling involves no fans, so a heat sink that does not have a fan attached is known as a passive heat sink.

Figure 3.18

Figure 3.18 Heat sink and fan

The largest chip on the motherboard with a fan or a heat sink attached is easily recognized as the processor. Figure 3.19 shows an Intel Core i7 that has a fan and a heat sink installed. Notice the heat pipes that are used as part of the heat sink.

Figure 3.19

Figure 3.19 CPU with heat sink and fan attached

Additional motherboard components can also have heat sinks attached. These are normally the chipset and/or the I/O (input/output) controller chips. Figure 3.20 shows a motherboard with these cooling elements.

Figure 3.20

Figure 3.20 Motherboard heat sinks

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