10 days ago, When I press the button to boot up my computer and the compter lights inside the unit flash on momentarly as do the cooling fans and shuts right off. Less than a second. 5 days ago I pressed the button again and the computer booted up and ran normally. Today it was back to flashing on and turning right off. I can hold the button in and it does this in succession on off on off etc. I took out the sound card video card and unplugged everything that draws power except the CPU and the same thing on, then off within 1 second Motherboard is a 790i by EVGA PSU is Silverstone OP850 Watt This unit is not that old, not that many hours on the build. Any ideas?