The specs for the NorthQ 4775-500BULK PSU are: +5v@30A, +3.3v@33A, +12v1@20A, +12v2@20A, -email@example.comA, +5VSB@2.5A. It looks good on paper.
The specs for an Antec Earthwatts EA500 500W are: +3.3V@24A, +5V@24A, +12V1@17A, +12V2@17A, -12V@0.8A, +5VSB@2.5A.
Since they both are 500W PSUs, they should have similar specs. I know that the Antec can exceed 500W.
For testing purposes, can you install a video card that draws less current to see if your system still crashes?