Well, I have gone in and reflashed it to the f21 BIOS. I have entered all the settings I had previously on the f7 BIOS, and it only sits on the Apple logo, no progress bar. I shall toggle verbose mode to see what it says. if anything.
I can't say I've had much issues with Gigabyte boards and hacks, up till now. My backup machine is a Z170-UD5 TH board with a i7-7700K, PowerColor RX 5500 XT, 32GB DDR4, and running Ventura the same as my main hack.
I don't see the point of forking out for a Z790, when this board works great, has plenty RAM, and still 2 free slots that I can stick another 64GB in. I use these machines mainly for PhotoShop and Iillustrator. So, yeah, I can use the processing power, and, basically, as it's my livelihood, and it's a tax write off. I figure if I'm over in the USA, and parts are a fair bit cheaper there (I'm in the UK) I pick them up when I can, besides I can sell the 12900K to offset some of the outlay, same with the GPU if I can get a working upgrade. Its just a PITA that so far this BIOS update has been annoying.