I'm having problems getting my PC to power on. Initially I thought it was the PCU but with a bit of troubleshooting i'm not sure now... I've ran around the usual pins with a multimeter and all reads out ok.
If I short green wire with the PCU connector connected to the motherboard then nothing happens.
However, if I disconnect the PCU connector, short the green wire (fans run) and then connect PCU to motherboard (green wire still shorted) by pressing the motherboard reset switch everything powers up fine (I ran the system for 1 week like this).
I've tried removing the green wire from the PCU connector allowing me to short this whilst leaving the PCU connector connected to the motherboard but its just the same.
disconnect the power switch and the reset switch fromt heir motherboard connectors and see if shorting the green wire will boot up the pc while its connected to the motherboard. I've seen where these switches can short causing a problem like yours.