Cant even get into safe mode? That is an unforgiving mainboard! I just pulled a EVGA 8800GTS out of my old shuttle SN27P2 gaming rig and put in a cheap old gigabyte 8500 to free up the second slot for a TV tuner to make that rig a HTPC. I didn't get that..
I'd definitely try a repair install first - seeing you have game installs on there
Asinus asinum fricat