Well, first of all you need to consider several factors why you pc overheats.
Even though computer has a cooling fan in their power supply, and processor (normaly seen cooling fan) Those 2 fans has only one job. The power supply fan only cools the power supply and the goes to processor fan. You have to least 1 to 2 hours close your computer. Closing it when not in use can be very helpful. Even though computer are in their hibernate state, its computer parts are still running.
Dust is the common factor that can make you computer parts run abnomally. If this parts cannot run normal they will force itself to run on its original speed making it warmer every second. Make sure that you clean the inner part of you pcevery week or once every two weeks.
3)EXPOSURE TO HEAT
When your using you computer it generates heat so it not advisable to put you PC where heat is at his peak. Not the to the point of melting if your thinking about peak. Put some fan/cooling fan in you PC. There’s a lot of slots where you can install 1 or more cooling fan.
If you have any questions feel free to post it here.