Not sure if this belongs on here or tech support. Since I know this is an issue on the game's end and not my own, I'll just go ahead and post it here.
Apparently this is a longstanding issue that has remained unresolved for about a year now: While running FFXIV in DirectX 11 with certain types of graphics cards, the GPU will abruptly crash, forcing the player to do a hard reboot on their computer. This issue does not seem to have any relation to the performance level of the graphics card, it just simply seems to glitch out with certain GPU's of Nvidia and AMD make. I'll relate my own experience here to demonstrate this.
I've played FFXIV since it's launch using a graphics card in the GTX 700 series (I believe it was GTX 750i). The game ran fine on that graphics card on max setting, and even when i belatedly figured out how to turn on DirectX 11 (thanks to its unusual placement in the FFXIV launcher) my computer still ran the game without any issues. Then I went out and bought GTX 980, and problem popped up where none existed before: At random times while running FFXIV, the GPU would abruptly crash. I can still hear the game's audio, but the screen is blank and the input seems to be unresponsive. At first I thought I'd fixed this problem by contacting Nvidia customer support and adjusting the GPU's power saving settings, but after this time I only really did social things in game over the next week while Fallout 4 took up most of my time (which I'm having no issues with in terms of GPU). Then a couple weeks ago, when I started to get back to doing some PvE stuff in FFXIV, I found that the bug that was causing my GPU to crash was still very much alive and well. After crashing several times in the course of a single night, I was forced to switch over to DX9 in order for the game to be even remotely playable.
So I did a bit of research after this and found that apparently this has been a known issue for close to a year. Apparently this bug is especially prominent in the GTX 900 series and certain types of AMD graphics cards. Some users have been able to fix the issue, while others seem to have had no such luck. At the moment, there seems to be no universal fix for this bug whether it be adjusting power saving settings, updating drivers, reverting to an older driver, turning off certain visual settings in game, or turning off certain features Windows GUI that may be interfering with the game. Every online discussion that I've been able to find relating to this issue dates to around this time last year, and none of them seem to end with the participants in the discussion reaching a conclusion on how to fix the problem, meaning that there are other users experiencing the same issues as I am who still have yet to find any sort of fix for it.
I must say, I find it irresponsible that this bug has persisted for so long and has not been addressed. It hardly seems fair that I put down over $300 to upgrade my graphics card so my games would look better only to discover that I am unable to play one of my favorite PC games in its optimum setting because of a GPU-crashing bug. I do hope that this issue is able to be resolved at some point in the future, because I am rather disappointed that I have to settle for inferior visuals due to something that is out of my hands.