The various components of a computer system such as the chipset, the graphics card and the hard drive can produce a large amount of heat while operating. This large amount of heat may be harmful for the proper functioning of the system. The heat sinks and the fans are responsible for dissipating this heat and maintaining the safe temperature limits.
The most important factor which determines the selection of heatsink assembly is the processor type and its speed. Different processors have different operating temperatures. Higher the speed of the processor, the better the heat sink and fan need to be. Similarly, the type of processor also determines what heat sink would go with it. The chassis type is also important as it defines the housing of the heat sink assembly and compatibility with the system.