I have an all-new PC with nice parts, Windows 10, all the latest drivers and software.
I did not change any settings on the 6900 TUF. I have benchmarked it and done thermal tests, and it runs really cool. I keep the temperatures monitored at all times and pay attention to fan speeds. The card is not overheating.
I made a huge custom Civ 6 game and maxed out all the settings, and played it for a while. It went several hours with no issues. Then, after many hours, the video signal cut out. The PC did not crash - just the GPU. It was not a software crash - the video signal stopped being sent, and the rest of the PC stayed on. I restarted and checked for abnormal temps and found none. I resumed from an autosave, and the same thing happened a few minutes later - loss of video signal, all other parts continue running.
As I said, I kept an eye on the temps the whole time. The room is cold, the case has 7 external fans, VRM fan, two RAM fans, and everything is underclocked except the GPU. It wasn't overheating.
Is this a known issue? What is the cause?