They also use cooling fans in the CPU. This is very essential as the computer while running generates a lot of heat. Also you must have heard that computers are installed in the rooms which have air conditioner. The Cooling fan is a small fan which helps in cooling the electronic devices to draw cooler air into the case from the outside.
It works the opposite of an exhaust fan. The exhaust fan throws out the air from the room making space for fresh air to roll in, while the cooling fan sucks in the cool/normal temperature air from the outside and throws it inside the case in turn pushing the hot air out and help cool the electronic device. As the components inside the case of the computer cannot dissipate the heat efficiently if the surrounding air is hot, the cooling fan helps this process and keeps the CPU cool for longer hours. It is a must in every computer.
We should not under estimate the heat produced in the CPU as this heat when tested is so high that one can cook their whole meal in this heat. The heat generated by the CPU could damage the components in the CPU and reduce its life span. You might end up having to change the components very often; therefore a cooling fan is a must. It is small in size fan and can fit into the CPU case very easily.
Cooling fans are used to aerate the case of the computer. The CPU cooling fan is used to cool the CPU heatsink. The Graphic card Fan is used to cool the graphic processing unit. Chipset cooling fan is used to cool the Northbridge of the motherboard's chipset. The other types of cooling fans are less commonly used are PCI slot fan, Hard Disk fan, and CD burner fan.