If that is so then you need to look inside the case for the problem I think. Try rerouting any cables that carry data away from cables that carry data away from any power cables. How long has this problem been occuring, since new?
No I couldn't hear any noise at all apart form the bump at the beginning. That was with the sound turned right up too.
As I said just now it is probably to do with the wiring runs. The only other thing that springs to mins as a possibility is the fans. Try putting your finger on the centre of each fan in turn to stop them and see if the noise abates. It could be one of the fan motors that is causing some feedback through the system.
Yes quite possibly. If you can remove the screws so that it is free you could try moving it and see if that makes a difference.