Game keeps Flickering to black screen when in fullscreen mode (PC)

Hello everyone when I start the game if I am in fullscreen it just constantly goes to black then back to normal then black etc. If I change to windowed its fine has anyone else had this problem I have checked all my graphics card updates and they are current.
(2x Nvidia GTX 1080ti SLI.) Any help would be appreciated or at least a point in the right direction.