No idea if the operating system will support nvidia graphics cards on arm. However, even if it does, the mac pro only has one 8 pin power connector and two 6 p

No idea if the operating system will support nvidia graphics cards on arm. However, even if it does, the mac pro only has one 8 pin power connector and two 6 pin connectors. The 4090 needs a 16 pin input, and I've only ever seen adapters that convert 2x8pin to 16. Maybe you could get one card running, but any more than that and you will need some kind of hacky external power supply setup.