motion blur and depth of field. I turn them off anyway.
Depth of field has no business existing in a game. In real life, you don't see that way, it's an effect of trying to emulate cameras with lenses. Technically, other distances are blurred to your eyes, but then when you look at them, they're clear because your eyes focus on the new depth. With DOF in games, I get one distance that's in focus, and if I look around, I see a blur, where if I were really there, my eyes would focus. There's no real way to emulate the way eyes work (which always seems to be what supporters claim dof is) without some sort of eye tracking to continually adjust what depth is in focus. What they're really emulating is a limitation of cameras, and I don't know about you, but adding in limitations that the technology doesn't need just seems silly.
Now, when you are playing from the point of view of looking through optics (e.g. a rifle scope), then depth of field seems perfectly natural and cromulent.
Motion blur is never implemented in agood way that I have seen. If you can see it, they've done motion blur incorrectly. If it smooths the motion, without being visible, then it has been done properly.
Using 2 680s in SLI, it's rare that I must turn anything down, but supersampling (when you're already at 2560x1600) tends to kill performance (what the witcher 2 calls ubersampling is this), so that's first. AA next. Other than supersampling, it's rare to need to turn anything down.