M2-ATX starts back up briefly after ignition-off
I've been running my carputer for a couple months now and managed to get all the little fiddly bits sorted out, so it's getting pretty complete.
Only thing left that is giving me grief is some odd behaivour of the PSU. Sometimes after losing the +12v on the ignition wire and properly shutting down, the system will turn back on for anywhere between 5-20 seconds, at which point it will hard-off.
This wouldn't bother me if it didn't normally hard-off in the middle of the resume from hibernate! It means that next time I start the car properly, the pc doesn't resume from hibernate properly, instead sits there with a boot menu asking me if I want to resume from hibernate since the last attempt apparently failed.
I've ruled out the +12v ignition wire in the car as I have a switch inline with it for manual control; problem still occurs if I turn this switch off. I've also ruled out my car's electrical system (I believe), as the problem still occurs when I rig the carputer up to a (good quality) PC power supply.
The M2-ATX is set to P1 mode, and I've checked, double-checked and triple-checked the all the wiring, so I'm at the end of my tether... dodgy unit?