It's a problem with the game client.
(1) Turn off all applications that create an overlay. FRAPS, MSI Afterburner, EVGA Precision, Geforce Experience, etc.
(2) Are you overclocked? Revert to stock and try that.
(3) Here's where you get into trying weird solutions. Hopefully you haven't gotten this far. Reddit post has more:
http://www.reddit.com/r/ffxiv/comments/3avur2/dx11_client_possible_fix_if_your_game_keeps/
Good luck. It took me 4 days to fix my crashes with my new 980 Ti.
Tried everything here. Unless there is something new in the thread, nothing has helped. I'll look again. This needs to be fixed.