I've been getting this issue now for about 2 weeks. I had it previously but it stopped randomly. Getting real tired of it too. I've done the following:

Replaced the video card (GeForce 760 to an AMD R9 270X)
Reinstalled windows completely
Rolled back my computer to when it wasn't happening (seems to fix it for a day)
ran full hardware checks
lowered graphics to high desktop from maximum

It only seems to do this in FFXIV, BUT after FFXIV causes a system crash OR reboot (it's done both), my system will sometimes freeze up one more time right after rebooting and before I launch FFXIV.

I'm running FFXIV on an SSD drive. Think that might matter?