Could this be the problem you have.
I am having a problem with my carpc which has an M2-ATX and a Jetway Via C7 1.5ghz motherboard.
The PSU seems to work fine but when I leave my car and come back in the morning the PSU refuses to start. The fans start spinning and the screen turns on but there is no POST.
If I hold down the power button for a long time it turns off and then if I press the power button again it sometimes POSTs and sometimes does not.
Also if I unplug the power completely to my PSU and plug it back in the thing boots up fine.
Any ideas? I have a PIC burner and can modify the ASM code if that will help or change any resistors.