F36 final for my x570 Master appears to have corrected my boot problems--booting much faster, as well. We shall see.

I read a post on reddit/AMD the other day that seems to have panned out. Guy was having boot problems with several different x570 mboards (Asus & GB) and solved them all by setting his vcore to "Normal" and then offsetting his vcore by some slight negative voltage. I was having boot problems...

Interesting, my thumb drive is cool as a cucumber and inserted the back panel port for the last ~3 years....;) Generally, a thumb drive only heats up when in continuous operation, I've noticed. You don't leave it in "a" port, you leave it in the port marked "BIOS" on your back...

Do you have a thumb drive that you use to update your bios? If so, leave it plugged into the back port marked BIOS permanently, and when you get all of your bios settings like you want them, save the settings profile to the thumb drive--not to one of specific positions inside the bios you could use....

Bingo....

F36f is perfectly stable here. This bios version is released for use on the main Gigabyte site, and they usually won't do that if a bios version is unstable. I have the same motherboard. It's been the best bios yet, imo.

X570 AORUS MASTER (rev. 1.0) Support | Motherboard - GIGABYTE U.S...

The AGESA is only part of the code...the rest of it is custom code to support your particular motherboard, manufactured by your particular OEM. The OEMs are constantly squashing bugs they find in their specific motherboard hardware--hence different bios versions using the same AGESA....

Ditto...F36f...no USB problems, I'm still on my 3900X...bios version is very solid....

9900x? Very few troubles for the last two years with my x570 Aorus Master. Runs like a top....

Hmmm...I just installed it to both bioses without a hitch. All I can think of is, per the manual, make sure that the mechanical switches are correctly positioned to allow for the backup bios to be flashed at the same time. That's probably not your problem, but it's all I can immediately think of....