In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 660 Gigabyte OC 2GB Edition SLI are noticeably better than the AMD FirePro S9150.

The GTX 660 has a 133 MHz higher core clock speed but 16 fewer Texture Mapping Units than the FirePro S9150. The lower TMU count doesn't matter, though, as altogether the GTX 660 manages to provide 6.9 GTexel/s better texturing performance. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The GTX 660 has a 133 MHz higher core clock speed than the FirePro S9150, but the FirePro S9150 has 16 more Render Output Units than the GTX 660. As a result, the FirePro S9150 exhibits a 8 GPixel/s better Pixel Fill Rate than the GTX 660. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The FirePro S9150 was released over a year more recently than the GTX 660, and so the FirePro S9150 is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the GTX 660.

Both GPUs exhibit very powerful performance, so it probably isn't worth upgrading from one to the other, as both are capable of running even the most demanding games at the highest settings.

The FirePro S9150 has 12288 MB more video memory than the GTX 660, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the FirePro S9150 also has superior memory performance overall.

The FirePro S9150 has 31.6 GB/sec greater memory bandwidth than the GTX 660, which means that the memory performance of the FirePro S9150 is noticeably better than the GTX 660.

The GeForce GTX 660 Gigabyte OC 2GB Edition SLI has 1920 Shader Processing Units and the FirePro S9150 has 2816. However, the actual shader performance of the GTX 660 is 2108 and the actual shader performance of the FirePro S9150 is 2534. The FirePro S9150 having 426 better shader performance is not particularly notable, as altogether the GTX 660 performs better when taking into account other relevant data.

The GeForce GTX 660 Gigabyte OC 2GB Edition SLI requires 260 Watts to run and the FirePro S9150 requires 235 Watts. We would recommend a PSU with at least 600 Watts for the GTX 660. The GTX 660 requires 25 Watts more than the FirePro S9150 to run. The difference is not significant enough for the GTX 660 to have a noticeably larger impact on your yearly electricity bills than the FirePro S9150.