Won't power off - only reboots on operating system shutdown/power off commands

[orbitwebsig]

So I've built my 1st system (had some RAM trouble, but got passed that).  Everything's looking great, until I issue a shutdown command (using Ubuntu 12.0).  I've also issued the poweroff command, etc. - nothing shuts the machine down, but instead they only result in a reboot.

I have the Gigabyte GA-A76M-UD2H motherboard, with the Award BIOS.  I've tried various changes in the Power Management Setup screen of the BIOS -  still only results in a reboot.

I was hoping one of the experts here would be able to guide to resolution?

Many many thanks in advance!!!

[Dark Mantis]

Hi

I don't know that much about Linux so I can't help on that front but I would suggest loading the Optimised BIOS Default settings and then disabling all the power saving options that you can find like EIST, C1E, C3, C5 etc etc along with all the sleep settings in the BIOS then save and exit. See if that helps at all. If it does you can try enabling them one by one until you find the culprit.

[orbitwebsig]

Ok, I did that - loaded the Optimized BIOS Defaults, and then made sure there were no power savings options set.  It was a good thought, but the machine still won't shutdown without a manual "hold the power button in" - could it be a wiring issue with the case/motherboard?  Or a short somewhere?