Hello, I bought my Mac Pro (2009 Quad) second hand. Power supply that is inside has already been replaced once. The thing is, my Mac Pro makes noise. I found out that this noise is caused by one of the fans, to be more precise, there is some vibration that causes the noise. For example if I push hard on the removable side plate the vibration goes away. If I want the noise to go away I have to knock few times on the side of the case but it usually reappears. Also, having the latch (the one that holds the removable plate locked) open helps. After some fiddling around, I noticed that the vibration comes probably from power supply, if I knock on it gently, it stops but once I put on the plate back and lock the latch, it starts again. I'm not sure what to do really. The computer is under warranty until Jan 2013 but I don't want to take it to service and be computer-less. My hunch is that when the computer shipped, something got loose a little bit. Is there a way to take out the power supply and tighten some screws or something?