I've got a G4 DA 533, running Leopard... It has a 40GB (I believe its stock) IDE hd it it, with the OS installed there, jumpered as Master. I have an 80 gig IDE as slave on the same channel (yes I know its probably faster if I had the drives reversed..) The other IDE channel is the DVD drive. My problem is in the system preferences I have the box unchecked that says "put hard drives to sleep when possible". I also have the system set to never sleep. Yet occationally I can hear what sounds like a drive shutting down, or maybe spinning up. Sometimes its 1 click, sometimes its 2 clicks in quick succession.. I know that 'click' and 'hd' in the same post immediately raise red flags about a hard drive failure, and this is further elevated by the drives being so old. But they pass SMART tests and TechTool Pro didn't find anything wrong with them. I know they can still fail, I've had many drives in PCs fail so I know clicks are bad, and failures can occur despite passing tests, ect. So what I'm asking is, if the drive isn't dying, is there any other explanation? Some preference file somewhere that isn't getting properly reset by me unchecking the put the drives to sleep box? Is there another explanation for the sound, to be honest it doesn't sound like a dying click to me, every drive I've heard die (with a sound) has emitted a sound like a beep or a thunk or a squeek, this doesn't really sound like that, but I could be wrong.