Gigabyte Z68X-UD7-B3 / 2600K OC help

My old machine has the title mainboard and a 2600K CPU. I'm having trouble getting the OC to stick, or so it seems.

It will run 4.6GHz all day on pretty low volts, and 4.0-4.2 on stock volts. I've gone into the bios multiple times and set my OC settings, F10 and restart. When it POSTs, it shows 4.6 or whatever else I set it to just fine. It boots into Windows, and when I turn on CPUZ and HWInfo64, both report the stock clock of 3.4GHz. The voltage settings stick, though. About the only thing I haven't done is fully reset the bios.

Do you have all the speed step /turbo and other dynamic clock/ voltage control disabled? On my UD4, if the OC is unstable, it will default to the last good boot OC, but it tells me that when it reboots (with BIOS logo screen disabled anyway).

I tried speedstep on and off, and turbo clock on and off. No difference. It's almost as if the bios is glitching on me.

Do you have the latest nonUEFI BIOS installed? Also, why do you have XMP disabled? Are CPUZ and HWinfo the latest versions? You can try the Intel OC tool to check clocks/ stability as well. Make sure your power profile in Windows is set to max performance, and maybe even go through everything and make sure CPU power is at 100% on all states. Make sure your chipset drivers are installed as well, on Windows 10 it installs P67 drivers by default for me.

XMP doesn't play nice on this board. Insta-crash. I've read people are lucky to get 1866MHz memory speeds on Sandy Bridge/Z68. Getting the 2133 XMP profile stable is a pipe dream it seems.

I had the F10 bios for a long time, but decided to go to F9 to see if anything changed. It didn't.