[QUOTE=Matth;2561923]I wonder if the problem is -5v, which became optional in ATX 1.2, prohibited in ATX1.3 (but still included in many old design cheapies).
Or the switch from ATX 1.x to ATX 2.x, where the 12V was emphasized over the +5V, leading to cases where cheap PSUs with weak 12V and old style 5V, may work better on older 5V heavy boards.
My guess is the board wants -5V for something, and the Corsair follows the letter of current ATX and does not have it![/QUOTE]
Switching power supplies can be tricky. I would check the voltages with a volt meter. Compare the readings to the cheaper one and see where the difference lies. If there is none, then it is probably switching off because of a bad ground.