Swede,
After installing the StarTech Firewire PCIe card, I was able to solve the Shutdown/Restart issue on Gigabyte boards where the option "PME Event Wake Up" (Power Management Settings) is present.
As you already pointed out in your article dated August 7th, 2012, disabling the PME option solves many unwanted Restart issues. On a GA-H67MA-USB3-B3 board the issue is solved, but on a UEFI based GA-Q77M-D2H the option is missing and I don't know what to do next...