For a single card there are a few that work well with minimal stuttering but recommending one isn't going to happen because ymmv. I'm on 326.41 and it's pretty smooth with a single card and garbage in SLI with this game.
I regularly see 90-99% GPU usage in MP with a single card and so do most people? The low usage usage only rears its ugly head with more than one gpu.
Edited by Slightly skewed - 9/6/13 at 11:37pm