Update: I completely factory reset my system (rather than the "soft" Windows Refresh which I suspect does not actually reinstall all windows assets) and so far in my initial tests (i.e. running 5.1 dungeon with trusts, and teleporting repeatedly to different high population zones) I have not encountered any crashing or errors.
My assumption based on a LOT of troubleshooting over this past week is that a file the 5.1 patch constantly needs to reference (be it a Windows library or a graphic card resource) is corrupted or broken and all normal methods of detecting/fixing that file are NOT working. I assume over the year of owning this system, I've either downloaded something that altered that file (maybe a Windows or graphics card update) or FFXIV altered that file (or expects something to be where it isn't). I cannot see this as a hardware issue since this problem is affecting a number of users with various setups and the commonality and timing of the problem is THIS PATCH.
The working setup (so far) is Windows 10 ver 1903 and Nvidia Driver 398.35 (REALLY OUTDATED). I also lowered my graphics settings from Maximum to High. I have left everything else untouched (to include NOT turning off overlays or installing other programs such as Steam). I play on an external monitor (ultrawide, 34", 3440x1440 resolution).
I am incrementally imaging my system as I add more updates to bring my system back up to speed while stress testing in-between images.
Next Steps:
- Incrementally updating Nvidia drivers to latest
- Installing Steam (historically bootstrapper crashed during FFXIV patching so something must be conflicting?)
- Installing Discord (the overlay is blamed sometimes for crashes)
- Attempt Shadowplay while gaming (my system previously could handle this prior to 5.1)
If it helps, I will continue to post my findings here for other users affected by this problem, otherwise I'll stop bumping this thread.