Hi Dark Mantis,
Several other users in other forum(as I see in these few days that I'm roaming here, also people in this forum) and my self are experiencing the exact same error, my build:
i5-2500K
GA-P67A-UD5 (running F2 and afterwards F6 BIOS)
GA GTX 460 SO
RipjawsX 1600 8-8-8-24 (detected as 1333 9-9-9-24)
Crucial C300 128GB
HX 650
First of all, I'm gonna say that the very first time I turned it on after building, it turned on for a few seconds and then it turned off. So there is no excuse!.
Secondly, even if the CPU and RAM are running at stock frequency, the problem is still there. I ran Intel Burn Test (Standard and High), Prime 95(around 8 hours), Memtest86+(at least 5 passes) and they are all stable. CPU-Z and Core Temp are showing normal voltages and temperature.
But sometimes when I restart the PC it does that turning on for a few seconds and then it turning off. And sometimes when I turn on the PC from off state it does that turning on for a few seconds and then it turning off as well. Not always, but often..
And this "The system has experienced boot failures because of overclocking or changes in voltage. Latest settings in BIOS may not coincide with current H/W states" certain times it even canceled the saved profiles, and every single time I need to set them up again. Even if you reset CMOS and running everything at stock(like the first time I turned it on) it still have that problem!
Really, it is annoying. I am speaking not only for my self here. Gigabyte is awesome, your P67-UD5 as well, but for the money we have paid, at least you could fix this random cold booting annoying problem.
Thank you.