I've seen Guru3D.com get one to:
Memory: 1282MHz DDR
I'm running a Phenom II X4 940 (3.0GHz) quad core with 8GB DDR2-800 on a AMD 780G mATX motherboard.
My currently most played games:
GTA4 on PC
Gears of War on PC
Chronicles of Riddick: AODA
Call of Duty 4/5
Far Cry 2
I know that running a Core i7 rig has often been shown to be faster than Phenom II systems. I run 1680x1050 screen resolution in pretty much all games. I'm a big fan of being able to enable as much eye candy as possible. Why play a beautiful game at crap settings?
More shaders, higher speeds, more TMUs, same memory... (yeah, GTA4 is pushing my video memory to the limit). Would I see a difference? It's a cheap upgrade. As is, my games all run nearly butter smooth with the exception of GTA4 and Crysis. Crysis is only clunky when I push the AA to 8xQ and beyond. GTA4... I can't max it out. Don't expect this card would let me either. Maybe it would have higher minimum framerates?
The bottom line is the upgrade would cost me $30 straight up. Do y'all think this really would be that much of a no-brainer? Am I silly not to do this? The upgrade window closes in 7 days from today.