Can't OC AsRock z68 Extreme4 Gen3 anymore

Piereligio wrote: Some days ago I've had to reset my BIOS, since my PC didn't boot. The thing was curious yet, since I boot since years ago my i5 2500k at 4.6GHz and my RAM corsair vengeance at 1866 (from 1600MHz) with no one stability issue (I've a Thermalright Macho HR-02, it's very good, I didn't have heat problems either).  After the BIOS reset, it booted up normally, except the overclock started to don't work. Basically if I use the OC presets in the BIOS, the CPU multiplier APPARENTLY gets applied correctly, but Windows doesn't load any OC.  Setting manually the CPU multiplier from the BIOS, instead, I notice that the multiplier is locked at 37. And Windows doesn't load even that. I can't even set my RAM higher than 1333MHz anymore. Like if it wasn't enough, if I try using AXtu tool (AsRock eXtreme tuning tool or something like that), I find the same 37 multiplier limit that I encounter in the BIOS. And Windows doesn't still load it even. I'm on Windows 10 Anniversary Update (but I don't think it's related to the update, since I updated some week ago). I tried resetting the BIOS again more than once, tried flashing another BIOS, and I didn't fix it... Any ideas?

The Windows 10 Anniversary update (a fresh installation, or update from another Windows version? Seems to be an update) may have been weeks ago, but have you had any updates to it since then? Whether you know it or not, you've had additional updates.

Or did you do a BIOS update for Windows 10 recently, that you did not mention? Your symptoms are similar to using the Ivy Bridge compatible UEFI/BIOS, with a Sandy Bridge CPU, without updating the Intel Management Engine (IME) software.

At some point, you probably had an additional update to Windows 10 that is no longer compatible with the IME software you have. For that and other reasons, your OC no longer works.

Your description of the OC problem does not make sense in some aspects. Are you sure that your CPU and memory OC were working at all in Windows 10?

I have a ASRock Extreme 4 Z77 with a i7 2600k, Corsair xmp ram. This past Wensday my rig started same thing. No XMP, 38 max multiplier normally it's at 46x. Went to sleep that night with no problems. Morning was screwed with no OC. Had to be a Win 10 update overnight cause I live alone and I know I didn't fubar it.