RAM, single core turbo speed, and the total number of cores is general more important to ARCHICAD than the graphics card. But, a decent standards-compliant card is still needed. Doesn't need to be a top-of-the line card, although a recent story reports that with the drop in bitcoin pricing, graphics card availability is beginning to be good again.
I don't believe that ARCHICAD can take advantage of multiple cards, but don't see a reason to complicate long-term upgradability for your client by doing other than a single card.
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB
One of the forum moderators