In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 760 are noticeably better than the Nvidia GeForce GTX 660.
The GeForce GTX 760 and the GeForce GTX 660 have the same core clock speed of 980 MHz, but the GeForce GTX 760 has 16 more Texture Mapping Units than the GeForce GTX 660. As a result, the GeForce GTX 760 exhibits a 15.7 GTexel/s better Texture Fill Rate than the GeForce GTX 660. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.
The GeForce GTX 760 and the GeForce GTX 660 have the same core clock speed of 980 MHz, but the GeForce GTX 760 has 8 more Render Output Units than the GeForce GTX 660. As a result, the GeForce GTX 760 exhibits a 7.9 GPixel/s better Pixel Fill Rate than the GeForce GTX 660. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.
The GeForce GTX 760 was released less than a year after the GeForce GTX 660, and so they are likely to have similar driver support for optimizing performance when running the latest games.
The GeForce GTX 760 and the GeForce GTX 660 have the same amount of video memory, but are likely to provide slightly different experiences when displaying game textures at high resolutions.
The GeForce GTX 760 has 48.1 GB/sec greater memory bandwidth than the GeForce GTX 660, which means that the memory performance of the GeForce GTX 760 is noticeably better than the GeForce GTX 660.
The GeForce GTX 760 has 1152 Shader Processing Units and the GeForce GTX 660 has 960. However, the actual shader performance of the GeForce GTX 760 is 1189 and the actual shader performance of the GeForce GTX 660 is 992. The GeForce GTX 760 having 197 better shader performance and an altogether better performance when taking into account other relevant data means that the GeForce GTX 760 delivers a significantly smoother and more efficient experience when processing graphical data than the GeForce GTX 660.
The GeForce GTX 760 requires 170 Watts to run and the GeForce GTX 660 requires 140 Watts. We would recommend a PSU with at least 500 Watts for the GeForce GTX 760 and a PSU with at least 450 Watts for the GeForce GTX 660. The GeForce GTX 760 requires 30 Watts more than the GeForce GTX 660 to run. The difference is not significant enough for the GeForce GTX 760 to have a noticeably larger impact on your yearly electricity bills than the GeForce GTX 660.