Problems caused by overclocking Intel integrated graphics

[proline9876]

Z97X-UD3H-CF ITE (IT8620E)
Bios F6 previously updated from F5
Intel Core i7-4790K overclocked to 4600 MHz @ 1.2789 V
Windows 8.1

Is it possible to damage the Intel Integrated Graphics (HD4600) by overclocking? I attempted to do this using Intel Extreme Tuning (don't ask) via frequency only not voltage I believe, and the PC locked up after the third increase. On reboot the system got through the BIOS but would not boot/display. Eventually after receiving "A required device isn't connected or can't be accessed. Error code: 0xc0000225' I managed to boot into safe mode, disable the graphics driver and then reboot the system. Even though the graphics driver is disabled and I do not have a separate Graphics card, dxdiag shows Microsoft Basic Display as the driver even though windows is displaying at 1080p.

Thinking it was a corrupted driver I have restored the system from a known good back up but that resulted in the return of the no boot/display problem. I have cleared the cmos and loaded optimised settings but this has made no difference. I have not forced a boot from the backup bios yet.

Could I have damaged the onboard graphics or is the bios corrupted somehow and the backup is not kicking in. I'm really stumped.

[shadowsports]

Greetings,
Just FYI..  F8 or lower are the best BIOS(s) for the 4790K (devil's canyon).  The Broadwell (5th gen) specific BIOS don't always work well with 4th gen CPU's.  So I think you are ok with F6.

I've not used the Intel XTU.  If it is still installed, try disabling all OC, delete any saved profiles and uninstall the software. 

Can't say what will help, but you can try any/all of the following:

BIOS
CLR_CMOS - Load Defaults
If you are running Fast Boot, disable

In OS:
If using any utilities for OC, disable (first), then uninstall
Run SFC /scannow from elevated command prompt
Run Start Up Repair > Advanced Start Up Options
System Restore to a point in time pre-OC

Try disabling Fast Start Up and test boot

Worst case.  Back up your system (full disk image)

Hardware evaluation:
Install a fresh copy of windows and see if the behavior follows

I just don't have any experience with the Intel Utility to know if it increases voltage with an OC.  The 4790K will do 4400Mhz all day long.  Going for 4600Mhz and /or trying to push the onboard HD4600 graphics isn't worth the trouble.