First of all, thanks a lot for your help!
No, it does not appear on desktop or any program.
Not sure, if you watched the full video. The flashing blocks in AoE4 are, well, ok and one gets used to it. "Fortnite" and "AC: Odyssey" are another level. "Fortnite" here and there even crashed.
GPU clock: 1200MHz
Mem clock: 6700MHz
Started "Fortnite" and it is still a mess. Finally it crashed after half a minute in the first attempt.
I even tried window mode with lowest graphics settings within the game. No luck and a crash.
Other games are good so far, that is why I have not complained after I bought the card. "Dota 2", "AoE2DE", "CSS" are not impacted. Hence I thought of driver issues at the beginning. Only after "Fortnite" changed the game engine last week, it appears also here. Had some issues with a raster of blue dots before if I set shadow details higher than lowest, but I could deal with that.
I have the strong feeling, that this is a hardware issue. But I am curious about what it is. There must be a special part of the GPU that gets triggered by the newer engines or such. No clue. But it is nicely reproducible and very persistent. Best preconditions for bug hunters to isolate the issue 🙂
But even if I know what is wrong, I do not know how to proceed. Asus told me in the meantime, that outside of guarantee, they cannot help:
If the errors persist, we recommend that you have the graphics card checked by a local specialist.
Since we cannot offer you a repair of the card in Asus Service without a guarantee.