In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GT 640 are noticeably better than the AMD Radeon HD 5670 1GB DDR3 Sapphire Edition.

The GeForce GT 640 has a 127 MHz higher core clock speed and 12 more Texture Mapping Units than the HD 5670. This results in the GeForce GT 640 providing 13.4 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 GeForce GT 640 has a 127 MHz higher core clock speed and 8 more Render Output Units than the HD 5670. This results in the GeForce GT 640 providing 8.2 GPixel/s better pixeling performance. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The GeForce GT 640 was released over a year more recently than the HD 5670, and so the GeForce GT 640 is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the HD 5670.

The GeForce GT 640 has 1024 MB more video memory than the HD 5670, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the GeForce GT 640 also has superior memory performance overall.

The GeForce GT 640 has 2.9 GB/sec greater memory bandwidth than the HD 5670, which means that the memory performance of the GeForce GT 640 is marginally better than the HD 5670.

The GeForce GT 640 has 384 Shader Processing Units and the Radeon HD 5670 1GB DDR3 Sapphire Edition has 400. However, the actual shader performance of the GeForce GT 640 is 346 and the actual shader performance of the HD 5670 is 202. The GeForce GT 640 having 144 better shader performance and an altogether better performance when taking into account other relevant data means that the GeForce GT 640 delivers a slightly smoother and more efficient experience when processing graphical data than the HD 5670.

The GeForce GT 640 transistor size technology is 12 nm (nanometers) smaller than the HD 5670. This means that the GeForce GT 640 is expected to run slightly cooler and achieve higher clock frequencies than the HD 5670.

The GeForce GT 640 requires 65 Watts to run and the Radeon HD 5670 1GB DDR3 Sapphire Edition requires 64 Watts. We would recommend a PSU with at least 350 Watts for the GeForce GT 640 and a PSU with at least 400 Watts for the HD 5670. The GeForce GT 640 requires 1 Watts more than the HD 5670 to run. The difference is not significant enough for the GeForce GT 640 to have a noticeably larger impact on your yearly electricity bills than the HD 5670.