In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 660 Ti 3-way SLI are significantly better than the AMD Radeon HD 7970 GHz MSI Lightning BE 3GB Edition.

The HD 7970 has a 155 MHz higher core clock speed than the GTX 660 Ti, but the GTX 660 Ti has 208 more Texture Mapping Units than the HD 7970. As a result, the GTX 660 Ti exhibits a 170.4 GTexel/s better Texture Fill Rate than the HD 7970. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The HD 7970 has a 155 MHz higher core clock speed than the GTX 660 Ti, but the GTX 660 Ti has 40 more Render Output Units than the HD 7970. As a result, the GTX 660 Ti exhibits a 31.7 GPixel/s better Pixel Fill Rate than the HD 7970. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The HD 7970 was released less than a year after the GTX 660 Ti, and so they are likely to have similar driver support for optimizing performance when running the latest games.

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 GTX 660 Ti has 3072 MB more video memory than the HD 7970, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the GTX 660 Ti also has superior memory performance overall.

The GTX 660 Ti has 144.6 GB/sec greater memory bandwidth than the HD 7970, which means that the memory performance of the GTX 660 Ti is massively better than the HD 7970.

The Radeon HD 7970 GHz MSI Lightning BE 3GB Edition has 2048 Shader Processing Units and the GeForce GTX 660 Ti 3-way SLI has 4032. However, the actual shader performance of the HD 7970 is 2002 and the actual shader performance of the GTX 660 Ti is 3951. The GTX 660 Ti having 1949 better shader performance and an altogether better performance when taking into account other relevant data means that the GTX 660 Ti delivers a massively smoother and more efficient experience when processing graphical data than the HD 7970.

The Radeon HD 7970 GHz MSI Lightning BE 3GB Edition requires 300 Watts to run and the GeForce GTX 660 Ti 3-way SLI requires 450 Watts. We would recommend a PSU with at least 550 Watts for the HD 7970. The GTX 660 Ti requires 150 Watts more than the HD 7970 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 HD 7970.