First Time OC - 4770K, z87mx-d3h, Yosemite - Will not boot

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Dec 17, 2013
8700K @5GHz
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Hello all,

I've been running a solid rig for a while - dual booting Windows 8.1 Pro and Yosemite, but I'd like to try a mild CPU overclock.

I've got a 4770K in a z87mx-d3h cooled by Hyper 212 Evo. Default clock at 3.69GHz in Yosemite.

Idle temp: 27˚C - 34˚C
Load temp: 60˚C

Went to BIOS, attempted light overclock to 3.9GHz, booted back into Yosemite without restarting, no issues, processor now shown in About This Mac running at 3.89GHz.

Rebooted to BIOS, got a little braver and pushed the OC to 4.0GHz, booted back into Yosemite, temperatures were fine, system was stable, showing 3.99GHz in About This Mac. Tried a little more, CPU was stable at 4.2GHz with decent temps.

Satisfied, I shut down computer.

When I booted up a few hours later, system turned on, fans spun, then shut off. Powered up again by itself and posted. I got a BIOS error message about "boot failures due to incompatible BIOS settings." Went to BIOS, reverted CPU to stock 3.5GHz, booted back into Yosemite and saw that frequency reverted to 3.69GHz in About This Mac.

Booted into Windows 8.1, downloaded Gigabyte EasyTune to see if that might work. Used "Light OC 4.1GHz" preset and rebooted. Greeted with same BIOS error message, despite using the tool.

What's going on here? Why was I able to go from BIOS to Yosemite, see that the processor had indeed been OC'd in About This Mac, but didn't hold on reboot or through Windows? Did the system not do a full reboot from BIOS to Yosemite?

Again, I am pretty new to overclocking, so any tips or ideas are welcome.

Thanks for your help.
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