I've had this problem with my pc for about two days now, when I turn on the computer it has to reboot up to three times until it 'actually' boots but even then the screen doesn't turn on but it goes to energy 'saving mode', all the fans are spinning and the cpu/gpu work but the usb only work for a few seconds but then my keyboard and mouse turn off. My guess is that the mother board might be dying or is dead but I need a confirmation. Also if I'm correct, the multiple reboots are due to failed overclock but I'm not certain.