[UPDATE] - so my issue from yesterday (on page 2 now of forums), seems to be due to 3 monitors (5760x1080 resolution). It worked fine for Far Cry 3 (and other FPS I have; Serious Sam 3, Portal, Titanfall, etc), but it gives the black screen issue if using eyefinity for FC4.
I've seen some vids that people do have it running in eyefinity. Did it just work for you, or did you have to do anything (ie. edit any files, etc) to force it to work?
Regards,
Sanjay