Given the price of the AMD Radeon HD 7870 ($240 / 187 Euro), NVIDIA's GeForce GTX 660, if not also the 650, may have to best it in terms of performance, not just the HD 7850.
Alas, the performance charts provided by the folks at VideoCardz do not include a comparison between the 660 and 7870.
Instead, there are comparisons between it and the HD 7850, as well as charts of the GTX 650 versus the Radeon HD 7750.
Tests were conducted in several games, all of them at a resolution of 1920 x 1080 pixels (Full HD) and, probably, with anti-aliasing disabled.
GTX 660 proves to be around 30% better than the HD 7850, give or take. Meanwhile, GTX 650 scored 21% better than HD 7750.
There are charts of the cards compared to NVIDIA's previous-generation models as well. These, while not as relevant to us, consumers, are still quite telling.
First off, the GTX 650 proves to be 23% better than the GTS 450. That's all well and good, but we would have liked to see a faceoff with the counterpart from the 500 series (GTX 550 Ti).
Secondly, GTX 660 is ruled 62% faster than GeForce GTX 460 and 28% better than GTX 560.
Nevertheless, there is one other matter: the games used in the testing were mostly NVIDIA-optimized. Had the charts included any titles in whose development AMD had a stake, the differences would probably not have been so large.
Then again, performance advantages aren't the only things that NVIDIA's engineers tried to accomplish. What they also strove towards was a lower performance per watt, an area where the 400 series had great problems. Starting two days from now (Thursday, September 13, 2012), prospective buyers should keep the TDP/power draw in mind when browsing for a mid-range / upper mainstream board.
