It is necessary that in advance computers when the hot air released from the components is being circulated through the cooling fans attached to that device and prevents it from overheating or burning.

The top part of the processor gets heat up very fast and to maintain it we should apply a thin layer of thermal paste and a heat sink and place fan to draw the hot air away from the processor and other system components.
Along with the CPU coolers fans are used widely inside the PC housing, to make sure that there is sufficient airflow through out the case two fans are placed into the chassis one at the front panel and one at rear side of the case to exhaust the hot air and get fresh air inside the chassis.
Even extra fans can be placed inside the chassis for the hard drives, motherboard as well as devices having their power which give up warm air as even some of the chipsets release heat by using additional fans you can keep the system maintained from overheating by providing smaller fans to keep the system cool.
Even today the graphic cards are larger and come with a built-in memory modules and many more features and to keep it running more smoother they have a cooling fan being fitted to keep the chips cool and operating.
It is to confirm that proper rating fan and heat sink is very compulsory as it can generate sufficient airflow to the processor and circulate the warm air away from the processor which prevents the risk of overheating of the processor. If you have many devices and want to keep them cool you can install a small powerful fan that create loud sound when they are spinning and change all the old fans which are more quieter. Fans are available in the market with different sizes to fit all the situations air cooling is just passing air over and above the devices which generate heat and moving all the hot air out of the chassis.
The normal for most computers now in addition to the CPU fan is it will have one or two exhaust fans which will force warm air from the inside of the case to the outside. Today the two fans comes with a built-in power supply the PSU cool but it draws air inside out through the PSU acting as an exhaust fan. Also some extra fans can be fitted on front of the chassis to bring in cool air which gets circulated with the hot air inside the chassis before being exhausted outside by the exhaust fans.
Water Cooling is the advanced cooling system nowadays used for the computer as the PC’s are getting upgraded to high-end if you are capable of purchasing a kit as it is very expensive technology as compared to normal cooling system as it requires to install a pump and radiator style device system to be installed and the water cooling is better as compared to normal cooling system and it will run more far guieter than the normal fans. Using these systems you can handle the cooling system so much as a result push your system further by Overclocking components further to squeeze every bit of speed increase out of the system. The water cooling systems parts are CPU block, North bridge block and Video card block it doe not use the plain drinking water but a distilled water or de-ionized water or there are chances to save your system.