I just having same problem with my board, my solution was
take board off the case, to prevent grounding isssue.
remove all card, only left video card, memory, cpu, and PS.
see if it boot up or not, if not, swith one item at a time.
if yes.,
start to add one card at a time to test out.
yes, it take long time, but it will help you to figure out what went wrong.