Does anyone have any ideas what I could do or check? I upgraded about a month ago and ever since then when I put my iMac to sleep it, I can hear something turning on again. I assume it's the HD starting up. Same sound if you wake up your iMac. The screen usually stays dark though, but the iMac is awake. The console shows nothing at the second it wakes itself up and so I have no idea what the problem could be. I unplugged all USB and turned off bluetooth. Any ideas? I'd really appreciate it as the iMac is in my bedroom and it is rather annoying.