I've never had this issue before and this has just happened. My Mac is now booting up at 640x480 and under the display profile, it is showing as 0x0. I've tried a PRAM reset, uninstalling the web driver and re-installing and nothing is fixing it. I've switched Displayports on the card with no success. I've also booted into my 10.12.6 partition on another SSD and it is having the same display problems too on that OS. Does anyone know... Is this a sign that my GPU is starting to go bye-bye? I'm running on a DCI 4K monitor, so this is looking horrible at the moment.