Got what I think is a unique situation here. Got a new case. Needed one with enough room for two 240x120mm radiators for my cpu and gpu coolers. Got a Rosewill Rise case. Cheap and easy. I made a decision up front that I didn't want the the fans drawing air through the radiators and blowing that warm air into the case so both of them are positioned such that the fans draw air through them and out of the case. One up front, and one on the top. This meant that I would need to turn the 140mm rear exhaust fan around and make it an intake. I set everything up, powered it on, and heard a whine coming from the rear exhaust fan. I figured it was just the fan, so I ordered a new one. Came in today, and I installed it. This fan has the exact same issue. My best theory here is that given that there are 5 exhaust fans and 1 large intake fan, perhaps the pressure in the case is he culprit? The rear fan doesn't make any noise if I run it at low RMP, which is how I currently have it set up. It's connected to a manual speed controller built into the case. I'd prefer to have it attached to the chassis fan power from the motherboard so I can control it with software, but I don't want to tolerate the noise. Another thing I noticed is that if I cover the intake with my hand, the fan stops making noise. I'm doing this lightly mind you, not pushing in on the grating or anything that would alter the shape of the fan or its housing even a little. Has anyone else experienced fan noise as a result of internal case pressure or similar? Perhaps some recommendations?