When I try to run the game with everything maxed (Texture at "Fade touched"), the game opens in a window on my left screen. I figured out that if I choose "Ultra" instead of "Fade touched" then the game opens correctly in surround. For the detail, I use Flawless Widescreen.
Now you might say that this is because my PC is not powerful enough, but here are its specs :
Core i7 4790k
SLI GTX 970 Gaming 4go
Kingston DDR3 2x8 go
So correct me if I'm wrong but that should be at least enough to open the game on my 3 monitors right?

