I tried Shadows of Mordor fixed at 100 fps with v sync disabled and g sync works great.
However, when I play it with g sync, it experiences screen tearing even at 60 fps (which is mostly constant). And I know the game is fixed at fps of 60. turn off v sync, enable g sync in full screen and windowed modes. I've follow all the necessary steps (at least all that I've been reading about) to enable g sync and play Dark Souls 3 i.e.