Actually, the lack of availability of the M3A78-EM is the major reason why the ATi version was discontinued. And then the lack of availability of the M3N78-VM is why we discontinued the nVidia and move to the Intel model.
You're right, the nVidia cards do run circles around the ATi cards under Linux, hence why we switched. And at the time we went to the Intel, it was because nVidia was no longer supporting HDMI out on their integrated chipsets.
Yea, I understand the supply chain challenges you're having. This may be the "Achilles heel" of trying to to use consumer grade PC parts as a basis for the system. PC hardware evolves so insanely fast these days, it certainly outpaces software development on a project like this exponentially.
I hope you get it worked out.