I have a PC with a Gigabyte Z87-UD3H motheboard, i7-4770K processor, Corsair Vengeance RAM. I recently removed my CPU cooler to reapply thermal paste to the CPU and ...

Update: SOLVED! Thanks for the suggestions, I'm back up and running after triggering the BIOS backup restore by holding power and reset for 10 seconds, as in method 2 on Overclockers outlined here.