Sadly the system didnt pass the overnight test despite lowering DRAM MHz to 1600. Now for a cascade of troubleshooting into what the issue REALLY is... Strange, been using bios settings exactly as per anandtechs article for core2quads (see post #467). Same thing happens every time: when I come to check system in the morning it is completely unresponsive with a black screen and I have to do a forced reboot. No idea what causes this