Just got a 2009 Mac Pro. And I can't stand it. The Mac Pro makes this low pitched, oscillating humming noise. Not too loud...but definitely there. And because it's oscillating, I can't seem to ignore it. Ugh! I opened up the case and checked the location of the noise. Not from the hard drive. But seems to be coming from the bottom of the case. It looks like it might be from the CPU heat sink/fans. Is this possible? Should I return the machine? Nothing I've done seems to reduce the noise (pressing against the case, checking screws around the hard drive, cushioning the hard drive, etc). Help!