How Does a Computer Fan Work?

Written by kim linton
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How Does a Computer Fan Work?
(Matt Lauer)


Computer fans are powered by an electric motor that is connected to the motherboard or power supply. Case fans typically range in size from 40mm to 120mm, and CPU fan sizes vary depending on the type of CPU housing. The fan housing and blades are usually made of heavy-duty plastic or metal, and may or may not include special noise- and vibration-reducing adaptors. Some fans even have built-in temperature readers that adjust the fan speed according to the temperature inside the case. Fan connectors are either 3 or 4-pin Molex. A 3-pin Molex connects directly to the motherboard, while a 4-pin Molex connects to the computer's power supply.


Most computer cases are equipped with one or more fans, heatsinks and vents. Computer case and power supply fans circulate the air inside the case or laptop housing, then blow the hot air outside through the vents in the case. Cool air is then brought into the case, keeping the internal components at an acceptable temperature. Fans used to cool CPUs may also be equipped with a metal heatsink, which increases passive or convection cooling power.

Special Fans

Some modern 3D graphic cards come equipped with their own dedicated cooling fans. Because of their high heat dissipation, graphic card fans are necessary to keep the card's GPU and memory cool. Some gaming cards in particular can produce more heat than a CPU. Passive or convection cooling is often used in addition to the graphic card cooling fan.


Hard drives, CPUs, RAM, video cards and other computer components all generate varying degrees of heat. As computer components' power consumption and speed have increased over the years, so has the amount of heat produced by these components. The BIOS of some motherboards includes settings that allow the board to automatically measure the case and CPU temperature and adjust the fan voltage accordingly. Computer components must not be allowed to overheat or damage may occur. Computer fans extend the lifespan of internal components and keep the system running at optimal levels. Periodically inspect all computer fans to make sure they are clean and operating properly.

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