I'm curious, what is the a card right now you could get for 200$, compared to one in 2019 you could get for 200$?
I'm wondering how bad gpu prices have gotten.
why did you tell us the old specs that doesn't even matter, anyways make your computer isnt overheating and that your liquid cooling is working. it might be a driver issue so if the previous thing isnt an issue try reinstalling drivers.
have you tried custom resolution utilty? if not maybe use normal resolutions. I was having this issue when I was using a hdmi gpu instead of a displayport one.