So here's a fun topic that seems to get tossed around as much as anything else: what's the ideal way to setup case fans on a completely air cooled system for maximum cooling? I'm no fluid mechanics graduate, but from what I gathered from other sources (notably Silverstone) and some knowledge gained back as an engineer in school, I thought of the following:
- You'll want more air per given space in the case than in the environment. So-called positive pressure. This has the effect of all the little cracks in your case pushing air out (mitigating dust build up) and prevents recycling of hot exhaust air (which some will get sucked into the holes that don't have a fan blowing out). So this implies that your intake CFM should be greater than your exhaust CFM.
- While having a clean stream of air from one end of the case to the other is ideal, I don't think it really matters. Here's the thing: if a component needs airflow to cool down, it will have a fan with it. This fan will blow air across it better than any airflow the case fans could generate. Not to mention, I'm pretty sure a fan cannot accelerate air faster than a given velocity. A fan is designed to push air, on the same token, air can push a fan.
- Top exhaust fans are counter-intuitive if your intake CFM < output CFM. Yes, convection does cause hot air to rise and perhaps collect, but most of the heat is in the middle, where your graphics cards are. The average temperature inside the case is going to rise before top exhaust fans will have any real effect.
- On that note, the idea for the intakes it to bring in cold air as much as possible, thereby lowering the average temperature inside the case. This is so active cooling components have cooler air. Yes you could lower the average temperature in the case by blowing out hot air, but you run the risk your case having negative air pressure. Not only that, a top fan that's an intake would blow colder air directly on your VRMs and Processor... so doesn't that sound more beneficial?
In any case, this video alone pretty much convinced me of a lot of things.