I had this issue for weeks. I finally got it solved for me, but it may help others. Nothing else seemed to mess up except for FFXIV.

I ran MEMTest86 and found that my Ram was bad. It was GSkillz 2X4GB 2133Mhz. I turned my Ram down to 1600Mhz with stock timings 9-9-9-21 2T - It passed MemTest at those settings but it would still crash FFXIV.

Swapped out to my trusty Samsung Green 1.3v Ram and everything is running great.