Having a non-K version, i know the limited overclock capabilities (+4 bins from stock x39 turbo multiplier).
My Motherboard BIOS (P8Z77-M) have the option to go up to x43 on ALL cores, via manual tweaking.
Wanting to get a little more juice out of my chip, got the multiplier up to x41. Booted fine. Running Prime95 torture test (at all cores/threads), i confirmed via CPU-Z that ALL cores were running at 4.1GHz. As it was stable, I decided to change to x42 on the BIOS. Tested again and ALL the cores were stuck at 4.1GHz even with the multi at x42. Same thing at x43.
Scavenging on the net, I saw a guy on youtube running the same i7 3770 at 4.3GHz (same method, multi at x43, stock voltage) at an ASUS Board (the model was not informed). The question is: Is it a motherboard specific issue? Do i need to change another setting on the BIOS ?
If you need my specs, here it is:
i7 3770 (1.112v @4.1GHz) (EPU Power Saving disabled on BIOS)
ASUS P8Z77-M (BIOS 1709, latest)
GeIL Enhance Corsa 8GB (2x4GB) DDR3 1600MHz CL9 (I don't think it will make a difference on this case)