Supernova1138 :
At what resolution? 1080p or 1440p the 1080 is more than enough, in fact the 1070 will do just fine at those resolutions. If you're talking 4K you may need to turn some settings down in order to hold 60FPS consistently.
Would GTX 1080 SLI be enough for Doom @4K?
Doom was programmed to be optimized for Nvidia's GTX 10xx series, is that correct?