My system is a Phenom II x6, Gigabyte 78-LMT motherboard, 2 8 gig sticks of Nemix ddr3 ram, and a 'new' Sapphire Nitro+ RX 580 that I purchased on eBay. The graphics card as received was very clean, only a bit of dust, as if it was barely used (seller said that it was in a rarely used computer). It's connected via HDMI cable, I just installed it Thursday, and reinstalled drivers via the Radeon settings app. My old graphics card was also a Sapphire, so I had an older version of the Sapphire TriXX app installed. Both previous days I had the card, I've used it for playing World of Tanks and Vermintide 2 without any problems.
Tonight, after about an hour of playing World of Tanks, I got a weird graphical glitch that had elements of the UI, both the game and Windows 10, jumping around and artefacting, showing parts of my background and multiple windows, and window elements (like the minimize and close buttons) enlarged and in wrong places. I closed the game, tried minimizing windows, but the glitching remained, so I hard shut down the computer, and when restarting none of the errors remained. I've since uninstalled the old version of TriXx and installed the new version, and used it to check the health of the card for the functions that it can show.
So, my question is, does this seem to any of you to be just some driver thing, did I get a bum card and try and get my money back? I took a couple of pictures with my phone of what the screen was doing, but of course the bits that the phone captured were when it wasn't too bad.