I've upgraded from the G5 to the Mac Pro. When I install the G5 hard drive into the Mac Pro tower, the Mac Pro makes a continuous buzzing noise. I screwed the G5 hard drive into the Mac Pro hard drive holding tray just like you would do with a Mac Pro hard drive. The Mac Pro hard drives are fine but the G5 hard drive make the continuous buzzing noise, making me think there is a compatibility issue. Thanks for any feedback.