Bottom line, what is the most common configuration scenario with regards to your case fans and air flow? Do you use Positive or negative airflow and mainly why?
I ask because I'm making some changes to my case fans and have an opportunity to make some adjustments.
Positive or balanced. Reason being, if your fans are all exhausting air, then air has to seep in through unfiltered openings or cracks, creating dust. But, if you're going positive, don't go overboard and have only 1 exhaust fan for 5 intakes, or 6 intakes, reason being this can cause turbulence inside the case which creates a hot pocket. You can guess the consequences. =-)
So, let's say your case has 2 front fans, 1 bottom fan, 2 top fans, and 1 rear. I'd suggest you organize your fans like this.
Front : Intake / Intake
Bottom : Intake
Top : Exhaust / Exhaust
Rear : Exhaust
On my S340 Elite, I use this setup, so I can keep balanced flow, and maintain a good 'path' for the air to follow inside of my case.
Top : Exhaust
Actually, you'd be a little better off in your example making sure your exhaust fan rpms were lower than your intake rpm's so you create a more positive pressure which keeps air moving more efficiently.
You could do that too.
Generally set slight positive or as close to balanced as possible with intake fans sectioned mainly on filters for builds I do for others, works reasonably well and dust build up is pretty small. For my own builds as my cases are diffrent, they are pretty seriously negative so need cleaning often.
Positive pressure. It performs slightly worse in theory, but it keeps the case cleaner, and in my case, I'm not doing anything terribly intensive.
I usually use negative airflow. one good fan in the back will handle 99% of builds. Dust is a different issue, but if someone isn't goingto take the time to dust out their pc they probrably wont bother to clean the dust filters either which is just as bad.