Not trying to debunk what has already been said in any way........but with newer cases being designed better, and components being more efficient (producing less heat), is there a need for a slew of ultra-high performance, high-speed low-drag case fans? What I guess I'm trying to say is, are your temps that high where you need to break out the Applied Physics book to orientate a bunch of fans to keep your components from boiling? All that is needed 99% of the time is to be able to move the air that your components heat up, OUT of the case. Positive vs Negative air pressure to me really has one factor involved......dust. In environments where your PC is on the floor, in a house with cats and dogs or whatever, you may need to adjust fans to create one or the other to deal with dust and debris collecting inside your case and on your components.
Myself, I have 3 fans installed in my case. The 200mm fan in the roof, working as an EXHAUST. The 120mm fan that came with my Intel Water Cooler, mounted in the rear chassis position and working as an INTAKE (note: it is pulling in cold air from outside and forcing it through the radiator, thus not blowing air into the actual "case" at all). Lastly, a 120mm fan on the far side working as an INTAKE and blowing outside air onto the back of the motherboard. I really don't need that third fan, but it was the fan that originally came in the rear spot that most people use as an exhaust fan. I just decided to mount it on the far side of the case because there was a mounting spot for it, no other reason. Being behind the motherboard tray, what air that does make it in to the "case" is negligible. Long story short, I have slots for 6 more fans but I barely have the temps that warrant the fans I do have! All more fans would do for me would be create more noise and blow dust around more aggressively.
Really study your component and case temps, get a logical grasp on what your fans are doing for you. It may help to sketch it out on a piece of paper, it may show you something you missed. If you are about to buy new fans, look at whether they are designed for Airflow, or Static Pressure....and learn the difference. Too many fans can work against each other or cause other problems.
Sorry for the long post, believe it or not, this is the condensed version! I'm also not saying it applies to this particular conversation, but it is applicable in general. More times than not, a few good quality, well-placed fans will keep hot air where it needs to be......outside your case.
)
