I'm right there with you on the AMD front.
I've had a laptop that had some weird problems with the installer. I tried a bunch of creative solutions and ended up returning the laptop and buying one from the Qubes Hardware Compatibility List (HCL). Worked perfectly the first time, restored all my qubes and was back up and running in a few hours. Had all my files, settings, browser tabs, command history.
As long as you have current backups (and you should), changing computers is a dream come true with Qubes.
This motherboard is the first time I've had trouble when picking hardware from the HCL. It may be that the unit I have is defective and just ordering another of the exact same make and model would fix everything.