I posted this in the FFXIV forums as well since it is possible it might be the DX11 client that is the problem. I'm not sure if there is an issue with the drivers or the game client. I am currently running a Fury X but this problem was there when I was using my 290X.
I currently use a LG 29UM67-P. With the DX9 client, I am able to play the game in fullscreen at 75 FPS.
With the DX11 client, the Frame Rate Limit is set to 75 fps (Refresh Rate 1/1) but my FPS goes to a max of 60. The same applies if I play in Borderless Windowed. If I select Windowed, my FPS will go back up to 75. If I turn off the Frame Rate Limit in Full Screen, I will get 75+ FPS but get a lot of tearing. I set my Catalyst Control to have a max of 75 FPS and will still get tearing within the VRR of 48-75.
Added an album showing my FPS in both DX11 and DX9.
With DX11 the game is set to 75 FPS max but won't go above 60. I will post a screenshot of this later tonight when I get home.
edit: replaced image with album showing DX9 and DX11 FPS settings