PWR Good signal bad?

[morlok]

Power signal
I hooked up a flakey P3 mobo on the bench to a generic PSU, 250W from Circuit City.
The PSU fan spins up for a second or two, then stops.
I vaguely recall that there are TWO power good signals on the mobo.
What signal isn't being signalled to show this behavior?

I DID check for shorts, BTW.

[morlok]

>What signal isn't being signalled to show this behavior?

No signal at all, it turns out.
The mobo was set to sleep/wake mode for the power switch, remembering the ATX spec helped. You have to ground the power switch for 4-5 seconds for it to recognize the 'request'.
Funny thing was, even pulling the power plug wasn't enough to convince the thing that it had lost power, still had to hold the power switch grounded for the 4 sec.
Switching its behavior to ON/OFF instead of sleep/wake makes the power button respond 'correctly'.