i have no idea... what would happen if i flash back to F7 to see if it boots/works and it fails? can i flash back to a beta bios with the x6 installed?
i think i flashed to the beta bios with the old core installed....
However, since it is a gigabyte you have dual BIOS. You can set somehow (usually thru a jumper) which is the active BIOS. You can then flash F8H on one of them and F7 on the other.
Moreover, on my gigabyte even if both BIOS fail I can still load a BIOS from a specially built USB disk - using a soft from the Gig CD I can make a USB bootable and able to flash a BIOS of my choice - not sure if all Gigs have this feature, but mine is kinda lower end, yours should have it too.