you can use multiple screens BUT you have to set them to a certain res for the game to work please see this page for supported multi monitor resolutions
http://www.wsgf.org/dr/far-cry-primal/en
like ,many games not all resolutions are supported .. check also with your vid card maker for driver updates , and other support options , as yes i do indeed know Nvidia had a problem for a few drivers with How they handle multi monitor setups on some GPU configs
but i do think your limited to yes 3 screens not 4 on both AMD as well as Nvidia drivers currently..thats a driver limitation in most cases ..see your read me notes in your Nvidia or AMD driver packages to see what games are optimized for Multi-monitor support ..that crap changes monthly