Your PC keeps cool by blowing a constant stream of air through its case. The primary air mover in most PCs is the power-supply fan, although some systems have an additional ventilation fan built into the case. Even in relatively clean offices, dust can accumulate on the fan intakes and seriously obstruct airflow. Clean your PC’s fans and fan intakes regularly, especially if you hear a change in the fans’ one-note whir.

A heat sink needs a constant flow of air to remove heat. In most PCs, the internal fans provide the required airflow. Never leave the case off your system while it’s running. Going topless may lower the overall temperature inside your PC, but it also destroys the internal airflow patterns that keep your CPU and other components from overheating.

As a last note, your PC’s hardware is also sensitive to rapid changes in temperature, and this can be caused by turning the PC on and off. I’ve seen many people turn on their PCs for just a few minutes, check their email, and then turn it back off again. And they do this over and over. This is hard on the computer. Your best bet is to leave the PC on all the time. As long as you don’t mind the sound and the little extra power bill, trust me, the computer is fine running all the time. The second option would be to turn the PC on in the morning and leave it on all day before turning it off at night. Even if you are only going to use it a few times that day, let the PC just run. Turn your monitors off to save power. You can also use the PC’s power management features to do their job in the idle time.