A little late to the game here, but....
It was pointed out on another thread that the F15q BIOS seems to have problems with any overclock changes 'sticking'. You can change them in BIOS, but they don't continue on through to Windows unless you've done a CMOS reset and then set your OC.
I was having issues with this on my Z77X-UD5H where I was decreasing VCore in BIOS, but HW Monitor didn't show it in Windows, and a change to the F15r bios from HERE
was able to fix the problem. Now my BIOS changes are properly implemented in Windows. Makes life much easier
You also have to take into account the inherent variability between individual chips. Mine isn't stable at 4.5ghz below 1.270 VCore - at 1.265 I get WHEA errors, but can still run P95 for hours and at 1.260, P95 crashes. I've seen posts from people with the same chip running 4.5ghz at 1.200-1.220 totally stable.