Overlays can cause problems with FFXIV, I see NVIDIA GeForce Overlay in application information. Shadowplay might be the culprit.
I've had issues like this on and off for months and tried everything including resintalling drivers fresh and setting compatibility to Win 7/Disable Fullscreen Optimizations. The only thing that fixed it was lowering my GTX 970 clockspeed in MSI Afterburner like the above poster suggested. I guess it was the factory overclock that FFXIV doesn't like.