Hi,

this is a very complicate question, what video card would you use and will you use these cards as a cross-fire setup?

The computer specifications are also important on a build like this. what sizes will the screens be? 

For more information you should read the article in the link. Also Club3d does not manufacture video cards anymore. they do however manufacture the cables and adapters that would be needed for digital -signage (videowall) setups.

https://en.wikipedia.org/wiki/Video_wall

if you are looking for detailed information you can take a look at the forums of Nvidia or AMD