Hey hey guys watch it.... computer power supplies only made to handle resistive loads....
that means no inductive ones. i.e. brushed motors
To turn on an ATX power supply, simply short the PS_ON pin to any of the GND pins.... but this wierd one I don't know.
I suggest plugging the power supply in, put your multimeter on vdc, hold the black probe to ground and look through the pins with your red probe until you come to one floating at an unstable or strange voltage... then try grounding it with a resistor. If it goes right down, then you've found a floating control line.
The only problem you might have is if this one uses sourcing instead of sinking logic... but I don't think it would.
If you need any other help hit me up.
-Q