Why does my NVidia Quadro P620 graphics card behave bizarrely with insane visual glitches?

I have an NVidia Quadro P620, sitting inside an unmodified HP Z240 “workstation” PC, bought 2019. Running Windows 10.

I have tried (in multiple “rounds”):

No matter which drivers I try, or how many times I reboot, change various settings (as suggested by random websites or support personell), pull my hair, scream into the monitor, etc., *all result in the exact same, very frustrating, hard-to-describe, “sluggish” drawing of “many” GUI elements.

I have attempted to contact both HP and NVidia to talk to their “support” “people”, but they literally know nothing whatsoever about their products and have no interest in anything other than collecting unnecessary personal information from me and my computer. (The reason I quote “people” is that they appear to be robots, and “support” is quoted because they don’t give any.)

I went so far as to record the screen and then watch the resulting video frame-by-frame. And sure enough, it very clearly displays bizarre artifacts, notably with File Explorer and Firefox, where to the naked eye, the File Explorer windows appear to flash white before actually drawing the real background (dark theme), and Firefox does a very annoying favicon glitch every single time I open a tab. It’s not about specific software; it’s clearly something wrong with the way the visuals are produced on this computer.

Frame by frame, File Explorer gradually draws what should be instant, for a number of frames until the actual contents are drawn.

The end result is that this machine feels like complete trash, and I get constantly annoyed by using it.

I have in the past had numerous NVidia and other video cards, even on Windows 10, and never had this problem before unless there was no driver installed at all. It almost feels like it’s using some kind of “worst-case fallback mode” to display something on the screen while debugging GPU issues or something. This is simply not how it’s supposed to behave/look/feel. I know that for sure.

It’s been over two months since their last update on the NVidia webpage. I’m keeping track of any updates to it, but I have little hope that an update will fix this.

I really don’t know what anyone could tell me at this point, since I’ve “tried it all” myself already, but I’m desperate due to how deeply this affects me psychologically. I bought a complete PC specifically to not have to deal with nonsense like this…

These are the four first frames when I start File Explorer (the only modifications are the red rectangles, for privacy):

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