back in the windows XP days I found that I had much much faster GUI performance when I used a GFX card with a 256bit memory bus instead of a 128bit or a dreadful 64bit, something else that made a big change: automatic down-clocking, I had to disable it for my GPU processor, then it went smooth. basically you still need to do this today with the CPU, not sure about GPU.
I moved to macs since and kind of regret it, I have no chance to tune the system to optimal performance and have sloppy GUI with many apps. but it is more stable overall and less dropouts…
so I think if you get a gamer card and do watercooling, you are on the safe side, also make sure the card does not down-clock (to save power), or you might get hiccups of some sorts. I would go for a card with a 512bit memory interface.
why I know all this? I suffered a lot and hemorrhaged lots money for my tests back then.