i had a problem with my m2, it would start up the pc as soon as it booted, the cure in the book was to unplug the motherboard from PSU but this didnt always work so a resorted to switching on the m2 then the plug the pc in, which worked fine and then i just tried it again one day and it would start to work properly. Seems odd the controlboard is aware of the PC boot so why it tells the motherboard to start straight away is strange i am guessing there thinking is drain the voltage and whatever caused it will reset.
Is it possible that yuor's is set to boot when the temp reaches -10 maybe?