|Check the capacitors on your motherboard, are they bulging, burst or leaking? Look at the tops and the bottoms of the caps, as they could pop from either side. I only say this because the issue that you have sounds like a power problem.|
The good power supplies have less ripple effect than the older, cheaper one, so they have cleaner power. The old power supply maybe able to fluctuate a lot more than the newer ones, so they can power your board even with bad capacitors.