I flipped the bios switch on my GPU during the PC's operation. The PC turned off and back on but since then it isn't posting. Nothing was shorted, I reset the CMOS, reseated ram, checked the PSU, reseated the CPU, unplugged all devices, tried to run off integrated GPU without GPU, ... The GPU works fine but the PC isn't posting. Motherboard lights turn on, all fans turn on. Any ideas what might be the cause and how to fix?