I did a quick test with Kerbal Space Program.
Although I'm still looking for the option/setting to show the fps (I know I saw it in there somewhere) I turned all graphical options to the max.
Only when approaching "mach 1" and the aerodynamic effects start to show did it have trouble. I turned those one notch lower than full, and all was well.
Occasionally, when making rapid (that is, really dumb) moves (if your not "testing"), it would stutter.
I dropped the AA down 1 notch as well, as this is the quickest frame rate boost in most games, and I can do pretty much anything I want with a smooth frame rate.
Even flipped it over and landed it, mostly.

Control-able all the way down.
This is on a rocket/ship with 409 parts.
As soon as I find the FPS counter/graph, I'll update with
ACTUAL fps #s.
Edit: Most odd combo here. New video card, yet monitor is having trouble.
Priorities!
Edit #2: I put my signature on this one twice! Must be getting old.
Barracuda