My PC switched off the other day by itself and now I get no post, no beeps. Its and Asus P5B and I've tried different CPU and PSU on it. Drives spin up and onboard motherboard power LED on but no chassis power LED. Just the HDD LED permanently lit. Optical drives do not eject :/ It doesn't even beep when no RAM installed. CPU does not get warm, even without heatsink on.