At least half of the reviews linked in this thread used newer drivers for the 9600gt than the 8800gt, and as such, I consider those reviews invalid. However, looking at the cards' performance in Crysis, in cases when they use the same driver version, I can see that the the difference is about 25-30%. And I'm talking about cards with reference clocks, not a highly OC'd 9600gt compared to a stock 8800gt. Here's a few examples:
http://www.behardware.com/arti...nd-radeon-hd-3650.html
http://www.computerbase.de/art...2/17/#abschnitt_crysis
http://www.legitreviews.com/article/666/10/
So you can tell yourself the difference is only 10% in games that both cards get well over 60 fps, but when a game really stresses the cards, the performance gap widens considerably.
http://www.behardware.com/arti...nd-radeon-hd-3650.html
http://www.computerbase.de/art...2/17/#abschnitt_crysis
http://www.legitreviews.com/article/666/10/
So you can tell yourself the difference is only 10% in games that both cards get well over 60 fps, but when a game really stresses the cards, the performance gap widens considerably.