Positive Airflow Optimization
If you didn't know already there is a very easy way to have a clean, non-dusty case. Basically you want to have more intake fans (blowing air into the case) than exhaust fans (blowing air out of the case) because having 5 exhaust fans and 1 intake fan is gonna leave your exhaust fans "hungry" for more air inside your case therefore air will be sucked from idk... say unused fan mounts and get more dust in to your case. Having more intake fans also can improve your exhaust fans performance. Also use filters for intakes, really no point for exhaust (Silverstone makes some baller ones)
Thanks, what is a good GPU fan?