Is it okay to install a reverse fan at the back of my Montech King 95 Pro case?

You could technically set a reverse fan at the back as an intake, but it’s not the best idea. Usually, the rear fan is supposed to be an exhaust to help draw hot air out of the case. If your CPU cooler is a liquid cooler mounted at the top, then having it as an intake might work, but it’s typically more efficient to stick with the standard exhaust setup.

Putting a reverse fan at the back isn’t traditional, but you can make it work as an intake. Just keep in mind that ideally, you want to maintain a balanced airflow, so it might be better to invest in some additional fans for proper cooling instead.