Just installed a GTX 660 card in my wifes PC. I was watching her play and noticed that things aren't rendering as fast as I would expect them to, saw some jerkiness when she was moving around on the screen. I had her turn FPS on, its in the 50's when shes not moving, when she moves, it drops into the 20's and lower at times.
With this card, she should be well over 100 FPS even with all settings at maximum.
I checked to make sure it was running on PCIE 2.0, it is.
Her comp specs:
Windows 7 pro 64 bit
AMD Athlon II x2 2.8 gHz dual core
16 GB DDR3 RAM
GeForce GTX 660