Check that no external device is feeding back power to your motherboard! Some components may latch up and the BIOS may hang upon next boot attempt.
"Won't resume after sleep"
Things to check (I experienced both of them in the past):
- DisplayPort cable Pin 20 DP_PWR must NOT be connected and fed through by the DP cable. Usually caused by cheap cables not adhering to the DP standard (or by a cable actually designed to power a DP converter etc.)
- USB bus may feed a wrong, too high voltage back to the motherboard while the computer is in sleep or powered off. Usually caused by crappy chinese wall wart PSUs, feeding above 5.5V.