A few times a week my buddies and I get together and play some GTA4. This game has run flawlessly in the past on high with my GTX 285 2GB. Even with max chaos and rain I would experience no lag or reduced FPS. That has now changed since I popped in my GTX 470. FPS have dropped to 30 and the game play is really just unpleasant. I reduced settings and saw some improvement but nothing compared to the 285. I chalked this up as immature drivers but isn't this game mostly CPU dependant ? All other games such as BC2 play as expected with the 470 so I'm a little confused.
Did you uninstall the drivers before changing cards ? Logic says you wouldn't have to do this but I gotta wonder if the installation doesn't load some different stuff for different cards as I have seen this fixed time and again by a reinstall.
I originally tried to swap out one of my 200 series cards (using the the newest drivers) and reboot with a GTX 470 in its place. That was a disaster. Didn't realize that the 470/480 had specific drivers different from the 200 series.
Additionally, I know that if you are playing around with clock settings and 'crash' the driver, windows will 'recover' according to itself. At that point, your performance will be ruined until you reboot.
hmm... GTX 285 is on par with HD 5850 which is on par with GTX 470. So all those are on the same performance line. GTX 470 is ofc the slightly superior card. GTX 285 weakest but almost as powerfull as HD 5850. So ofc you shouldnt experience slower FPS since GTX 470 is slightly better than GTX 285 but remember GTA 4 is a memmory game. And GTX 285 2GB can most likely run it better. Besides GTX 470 is still very new. IT might be driver issues.