Computer Case Fan +

A computer fan is any fan inside, or attached to, a computer case used for active cooling. Fans are used to draw cooler air into the case from the outside, expel warm air from inside and move air across a heat sink to cool a particular component. Both axial and sometimes centrifugal (blower/squirrel-cage) fans are used in computers. Computer fans commonly come in standard sizes, such as 120 mm (most common), 140 mm, 240 mm, and even 360 mm. Computer fans are powered and controlled using 3-pin or 4-pin fan connectors.