Overclock recently being ignored in windows - ASRock z97 Extreme4 / i5-4690K

Hurlbag

Reputable
Aug 24, 2014
1
0
4,510
(TL;DR at bottom)
Hi so as title says, I have an overclock with my 4690k set to 4.2ghz with speedstep enabled which functioned perfectly since I first got the CPU/mobo, but within the last week or so I noticed all cpu monitoring programs show the max clock rate at stock (3.5ghz) even under 100% load (using Prime95).
I've tried all I can think of, flashing every version of BIOS and re-doing the overclock settings, all having no effect. I also noticed the voltage, regardless of what value I set it at will always show up as 1.218v (set as 1.3V in BIOS for stable OC). The only thing that allows my overclock to come through is disabling Speedstep, but for me that is not an option as I always had it on and it worked before, but now recently it's arbitrarily decided not to.

What gives? I really have no idea what else I could try and starting to get frustrated, i've tried disabling various CPU features but again no effect. Windows recognizes an underclock when I set it to 3ghz but that's about it. Stumped.
Any help would be much apprecaited.

TL;DR - 4.2ghz Overclock since recent is being ignored, showing stock values - nothing i've tried works to put it back, attempted all BIOS versions.