Random artifacts on RTX 3090 graphics card when running Unreal Engine. Is my GPU broken?(

Hi guys. I recently bought a 3090 video card, truth be told used, mostly for graphics work. When I work in Unreal Engine, for a split second twice in 2 weeks of use I noticed artifacts. The first time it appeared as a horizontal gray bar in the center of the screen, the second time as black squares all over the screen. I noticed that they appeared under heavy load (the first time when applying a console command when Unreal Engine was, say, frozen and performing an action, the second time - when importing assets from Megascans). What’s interesting is that artefaets cannot be replicated in other applications, games and even in stress tests like OCCT, Kombustor or FurMark. What could this be about? A bug in the drivers, in Unreal Engone, or am I getting ready to change my graphics card?