Hey I've had this build for a year or so: Win 7 Ult 64 (Daz loader) 3570k Extreme4 mobo Corsair CX600 PSU Samsung green RAM Samsung 840 SSD As of some time ago the PC started crashing and rebooting when put to sleep. I've since reset the BIOS (was stable overclocked slightly), still the same. Event viewer doesn't show anything. Malware/ virus/ rootkit free. THE last thing that I can think of being changed (cannot say the problem started happening here though) was me downloading some USB 3.0 updates from the ASrock website (I opted for no optical drive so I never installed the ones provided on the disk) This shouldn't matter but if it's USB related I've got 2 keyboards and mice connected, one set wired, one wireless (doubles as HTPC), external USB drive, 360 controller. I've searched and searched, people recommended changing the sleep modes in power management, none of that helps. TIA Edit: BTW, it WILL sleep, but sometimes it's on the first try, sometimes on the fourth.