Hey, here’s a brilliant idea: Let’s design a fancy high-end case with dust filters on all the intakes, then stick a bunch of random holes in the back.
Oh wait, everybody does that already.
That’s the Be Quiet Dark Base Pro 900, an otherwise very nice case but hardly unique in suffering from this problem.
Why does it matter, you ask? It’s not like there are fans on those grates. Well in the old days when the number of intake fans was usually greater (or at least comparable) to the number of output fans it probably didn’t matter as much, as you would create an overpressure situation in the case where air wants to escape, so the open grating would tend to vent out.
But this case, like a lot of high end cases, supports large top radiators. You can put a 420mm radiator in it, which means three 140mm fans pushing air out. Plus the additional output fan on the back (there’s no dust filter there after all so you’re probably not going to use it for intake…) means you have a total of four 140mm fans venting out. You’re probably not going to have 5 intake fans (I don’t even know where you would even put that many…). So unless your intake fans are running at a higher rpm or something you’re going to create a low pressure zone inside the case. Meaning that air wants to come into the case. And guess what, there’s a bunch of holes in the back! So air will come in the case though those holes. Holes that aren’t dust filtered at all…and tend to face the dustiest back corners of your room (let’s be honest…).
Honestly I want to just cover up those hole entirely. And maybe get a third party dust filter for the rear fan and turn it into an intake, doing all the venting out the top. But there are a lot of holes, and I can’t believe more case manufacturers don’t think about this sort of thing…