So one week ago Square Enix released expansion for ff14 with new dx 11 option. To be honest game looks really good with it but it's crashing every 10-20 minutes with dx11 enabled. Dx9 working just fine, can play with that mode whole day and nothing wrong happening. I'm not the only one person who have that problem. Game crash on new nvidia and radeon cards. Just check SE forum:
FINAL FANTASY XIV Forum (dx11 threat)
I'm using r9 285 gigabyte oc version.