It's H1Z1... that game it an utter mess optimization wise and I'm amazed you got higher than 60FPS, my GTX 970 went between 50-60fps no matter what settings on 1080p (I refunded that mess of a game)
Trust me if you played a game like Witcher 3 on for example you'd be playing ultra above 60fps. I can play Ultra textures and everything else high with AA on a GTX 970 no problem constant vysnced 60fps.
H1Z1 is not a good example of what the GTX 1080 can do.
Try running near to full maxed out:
Killing Floor 2
Dayz ARMA Mod
Assassins creed Syndicate
Then you will see what your GPU is really capable of.
Some games on 1440p need the settings turned down, especially the AA settings.