Computer fans are found inside the computer case and help prevent the various computer parts inside from overheating. Without them, components of your computer can malfunction, become damaged, or even crash.
A computer fan can do one of three things. First, it can draw cooler air from the outside and into the computer case; that is, it can pull in the air. Second, it can get rid of the warm air inside the computer; that is, push out the air. Lastly, it can move the air across a heat sink to cool another computer part, such as the central processing unit (CPU). A heat sink is a component that absorbs and dissipates heat. In this set-up, you can think of the computer fan and the heat sink as a tandem that works together.
A computer fan commonly comes in a square frame, although round ones are also available. The usual sizes are 60, 80, 92, and 120 millimeters (about 2.36, 3.15, 3.60, 4.70 inches). The size, of course, depends on where the fan will be placed. The computer case or computer chassis is where fans are usually mounted. They can be installed behind, in front, at the sides, or even on top of the computer case.
The CPU is one component that needs a computer fan to function well. The CPU is the computer's most important chip; in fact, it's often referred to as the brain. Thus, CPU fans are very vital to a computer's well-being.
Computer fans are also used to cool chipsets, which are sets of specialized chips on the computer's motherboard. Another common application is a graphics card. With the advent of high-powered games and 3D graphics, graphics cards generate a lot of heat, and graphics card fans keep them cool.
Fans are less commonly used on hard disks and power supplies. The hard disk is where all of your files are stored on the computer, and hard disk fans help prevent them from crashing. On the other hand, if a power supply overheats, then your computer doesn't get any juice, so power supply fans can be important as well.
Computer fans also vary in the amount of airflow and speed of rotation. Amount of airflow is measured in cubic-feet per minute (CFM) while speed of rotation is measured in revolutions per minute (RPM). A higher speed typically means more noise generated by the computer fan.