Thought Id share my experience here. Great piece of software here.
MBRWizard Suite Products which is mbrwizard

Recently on my win 8.1 config which consist of 2 120gb ssd (samsung 840 evos) non raid
and 2 toshiba 1tb drives non raid (but ran raid zero on previous config before the ssd with a efi partiion)

So to make a long story short one of my 1tb drives was completely locked up i mean locked up. showed in bios, didnt show in a raid config sw, didnt show in the admin tool disk management in windows 8x, and i couldnt even get it show in diskpart command line prompt thing, tried everything.

I was getting ready to send back to toshiba... but what it was a EFI GPT partition that was siezed up and this piece of software i was hestiant about it because i didnt see anything bout it support win 8 on the web page. emailed dev told me it was. So was cautious still.

So i said what the heck only 10 dollars. purchased and installed.

And well it fixed my locked up drive. detected it! repaired it! low level formatted it as well. Even has menus for win8, so yes it is fully win 8 support, just no efi bootable yet but he told me its coming soon.

Want a good util go check this out. love it