I had that DX11 crash, on a machine I was refurbishing.
This was after scrubbing all the SSDs, reinstalling Win10 from scratch, and then installing FFXIV.
Things would run fine for a while, then crash.

So ...
I ran the free trial version of BurnIn Test (from the makers of Memtest86) on the system.
Turns out that the CPU was overheating, due to several years of accumulated dirt in the fins of the CPU cooler.
Uninstalled the cooler, took it apart, washed it, dried it, reinstalled with new thermal paste.

I saw a 25C drop in CPU temps, and had no more problems.