Ok guys, I'm at the end of my rope. I have built a system and have had it running fine for a year now. I have a msi 570-g54 motherboard with a gigabyte hd 6850 gpu and a amd quadcore black edition cpu. For some reason around a hour after the pc has been on the monitor goes black says I lost connection and the sound cuts out. The tower and all the fans run fine. I replaced the power supply,check all the wires, and re-seated the gpu. I have no idea whats going on. All the temps seem normal leading up to the shut off..