Its not complicated, just don't even try and flash a bios from a different series or vendor to a mismatched card and take a chance of making a paper weight of your video card, simple.  If its a bios the manufacturer has approved for your card then go at it and enjoy, but only if you understand the risks in case the bios flash fails, could end up being a worst nightmare. Overclocking is a pretty simple thing anymore though once you have done it a couple times and understand it then your good to go.

I think it goes without saying that this is not officially supported...but I'll still say it anyway.

Although it might seem complicated/intimidating on the surface, it's rather easy, but when monkeying around and flashing a VBIOS, one should have a spare graphics card or a CPU with graphics (which an i7-990X does not have) so one can that to attempt to unbork it if it gets borked.

rjohnson11
Don't flash any video card with a non company approved BIOs. It's just not worth the headache and risks involved. 

True story.