I bought my pc about two years ago(factory model asus) and just recently upgraded to windows 8. I have also upgraded my GPU to a radeon r7770 and my power supply to thermaltake smart m series 850 watts. my pc one day just started rebooting. it only reboots if I go to the desktop in windows 8 I can use the windows tile screen just fine. Also I set my pc to not reboot on system failure and it still happens. My monitor goes black and then my backlit keyboard and mouse go dark and the whole thing reboots. it then tells me that windows encountered a problem and asks if I would like to send details. I also started it in safe mode and that stopped the problem but I still have no clue what is causing it.