Case Fans are fans attached to the CPU to cool down its temperature. It works by expelling hot air out and draw cool air inside. In this way, it keeps the temperature down. It also moves air on specific parts of the computer to maintain the temperature. Several types of cooler is been used in different CPUs according to their size and requirement.
These fans locate in different parts of the computer. Several fans could be used in the CPU. Such as on top of the computer processor, inside the power supply, on the video card, and on the side of the computer case to regulate the temperature.