Have you run a data check? I did that on Steam and I'll see the results when the download ends (it's big since it has to redownload HW). Also, if that doesn't work, I'll try out yet another driver downgrade, 350.12. That plus the PhysX option seemed to work for some people. Btw, if you're using the Steam version, more ppl are reporting this error and gathering data over there, in the discussions section.

Some dude said he fixed the issue by running another game (any works I think), then opening FF14 after the game was running. FF14 would run fine, then he could close the other game.

As soon as I find out something new I'll be back and update, good luck.