Not going to get into the technical bits, but just relay my own experience with a very similar issue last year. I have an Asus G752 laptop, i7 gen whatever, GTX1070 and all that as my secondary machine. Anyways on DX11 poof! Would kick me back out to Windows with an error, sometimes no error, sometimes would take the whole system down. Tried a lot of what you have, reinstall Windows (PAIN IN THE ARSE ON A GAMING LAPTOP...so many drivers <.<). Yet issue would persist. Now I'd been usin the same client download I'd had for a while, have never had an issue there with FF or any client based game for that matter but in desperation I downloaded a fresh copy (slowish internet then, potential overnight affair). Client in hand I set everything up and no issue at all on DX11 anymore? It seems to me that the FF14 client has no way to check and verify/repair files so I'm thinking that was my issue. If you haven't tried this maybe do so, after I had my experience (anecdotal) I've had talk with a fair few others who had similar experience. Good luck and nice machine xD