This probaly wont be any help but I had a scare just last night. My machine froze up, tried to reboot but it wouldnt even POST nor display anything. I tested vid card in another machine worked ok I was stumped until I saw massive dust bunny infestation in my CPU heatsink. I cleaned that off but it wasnt until I actually unplugged and plugged back in the machine that it would boot. I guess that the MB needed to be reset as it always has a diode lit up even when turned off at the switch, maybe its a safety feature.