The first generation GTX 460 1gb (256 bit) is a better card, but doesn't overclock nearly as high as the GTX 555 (192 bit). I've owned both and the GTX 460 topped out at 865 Mhz while the GTX 555 hit 1 Ghz. At those speed there was no difference in performance between the two. To confuse things further there is a GTX 460 v2 that was based on the GF114 just like the GTX 555. It sits between the other two in stock performance and also will overclock quite well.