The BIOS rom, is the file you download from Gigabyte.
First edit the bios, flash that with FPT.
Then flash another time with an unedited BIOS rom. From inside the BIOS with Q-flash.
So you need 2 files, on with the edit, one without.
It kind of concerns me they gave you the F6 Beta bios, and it didn't fix anything. Hopefully they will work on it.
I also got a reply from them, they told me to put Windows boot in UEFI. But it's already in UEFI.
Although I clearly stated that the problem only occurs with XMP, support hasn't been that helpful for me.