From new my Mac Pro tower has had an annoying high pitched squeal or whine when moving windows or scrolling windows on the screen.
The sound is not there all the time but only after the machine has been on for a few hours so it had to be heat related.
After spending an hour or two tracking down the sound it was coming from the Nvidia 8800GT graphics card which is fitted as standard into the Mac Pro’s.
Other blogs and forums suggested that the noise is caused by the inductors on the graphics card resonating when under load and needed to be fixed down.
After removing the graphics card and taking the heatsink cover off which was held on with cross head screws, I found several large inductors on the board.
I painted a small amount of modelling gloss paint onto each side of the inductors and onto the graphic card main board to hold them in place, taking care not to get any paint on other components.
I let it dry for a few hours and reassembled the card and put everything back into the Mac Pro tower.
After 6 hours continuous use the sound hasn’t reappeared so it seems this has cured the high pitch squeal problem.
Only try this if you know what you are doing and don’t try it if your Apple Mac is still under warranty as I am sure that painting your graphics card be hard to explain if you have to send your machine back to Apple!