Hi there,
1 long 2 short could also be ram problems as the video uses system ram, I noticed you re-seated all ram chips but have you tried running with just 1 or 2 chips?
Failing that it could be your board, noticed that your PSU is low wattage, may or may not be the problem, I have a corsair TX650 on my system.
You seem to have run all standard tests, hopefully you get it working, let us know how you get on.
Ben.