In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 660 Ti Power OC Edition SLI are very slightly better than the AMD FirePro S9150.

The GTX 660 Ti has a 119 MHz higher core clock speed and 48 more Texture Mapping Units than the FirePro S9150. This results in the GTX 660 Ti providing 69.9 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 Ti has a 119 MHz higher core clock speed than the FirePro S9150, but the FirePro S9150 has 16 more Render Output Units than the GTX 660 Ti. As a result, the FirePro S9150 exhibits a 8.7 GPixel/s better Pixel Fill Rate than the GTX 660 Ti. 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 Ti, 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 Ti.

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 Ti, 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 Ti, which means that the memory performance of the FirePro S9150 is noticeably better than the GTX 660 Ti.

The FirePro S9150 has 2816 Shader Processing Units and the GeForce GTX 660 Ti Power OC Edition SLI has 2688. However, the actual shader performance of the FirePro S9150 is 2534 and the actual shader performance of the GTX 660 Ti is 2949. The GTX 660 Ti having 415 better shader performance and an altogether better performance when taking into account other relevant data means that the GTX 660 Ti delivers a noticeably smoother and more efficient experience when processing graphical data than the FirePro S9150.

The FirePro S9150 requires 235 Watts to run and the GeForce GTX 660 Ti Power OC Edition SLI requires 300 Watts. We would recommend a PSU with at least 650 Watts for the GTX 660 Ti, but we do not have a recommended PSU wattage for the FirePro S9150. The GTX 660 Ti requires 65 Watts more than the FirePro S9150 to run. The difference is significant enough that the GTX 660 Ti may have an adverse affect on your yearly electricity bills in comparison to the FirePro S9150.