I have a 2008 mac pro with the original OSX drive and then two other hard drives, one I use for Boot Camp/Fusion and the other for my work files. Under Energy Save in system preferences, I have it so that the drives will sleep whenever possible. The issue I'm having is one of the drives, I think the one with my work files, will wake from sleep every 15 minutes or so even if I'm not accessing any of the files. I haven't timed it exactly but it's around 15-20 minutes and happens throughout the day. What is causing the drive to wake? I disabled iStat Pro because before the drives would spin every time I checked my dashboard so that's not the problem anymore. Any ideas? Thanks.