Hi Brian,
The question is difficult to answer, since it depends a lot on the content you’ll play in the experience.
If you plan to have mainly static content, 1 video playing at a time, any card able to output 4x4K would do.
If you plan to play 4 x 4K videos in parallel, a P4000 could be a good place to start. The RTX 2080 seems to have even higher specs, so it sounds like a good option, although we have never tested these cards.
You can check these other threads with other Intuiface users building multi-screen setups:
- Ideal system specs for an image wall - #4 by melvyn_br
- Video wall resolution - hardware configuration issues
- 12K video wall stress tests & VLC vs Intuiface comparison - #12 by carson
Guys like @Promultis or @mauricio actually have a better than us since the highest GPU we have in the office is a GTX 1070 