Nowadays, most cases have several places where you can put a fan. Supposing that you want to install only one fan on your computer, where is the best place to do it? Let’s run some tests and find out.

It is a well-known fact that the fans installed in the lower half of the case must be installed as intake, while the fans installed in the upper half of the case must be installed as exhaust, blowing air to the outside of the case. Because of the physics law which states that hot air rises, it makes no sense to force the hot air to flow downward.

In order to answer this question, we ran some tests, measuring the temperature difference between the CPU core and room temperature with the case fan at different locations: at the rear panel, at the top panel, at the front panel, and at the side panel. We also repeated the test with no case fan at all, with the case’s left panel closed and open. We will present the test methodology and results in the following pages.

Rafael Otto Coelho is a physicist with a master's degree in Education, and is a college professor in Brazil.