In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GT 640 are noticeably better than the AMD Radeon HD 4670 1GB.

The GeForce GT 640 has a 152 MHz higher core clock speed and the same number of Texture Mapping Units as the HD 4670. This results in the GeForce GT 640 providing 4.9 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 GeForce GT 640 has a 152 MHz higher core clock speed and 8 more Render Output Units than the HD 4670. This results in the GeForce GT 640 providing 8.4 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 three years more recently than the HD 4670, and so the GeForce GT 640 is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the HD 4670 when running the latest games.

The GeForce GT 640 has 1024 MB more video memory than the HD 4670, 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 4670, which means that the memory performance of the GeForce GT 640 is marginally better than the HD 4670.

The Radeon HD 4670 1GB has 320 Shader Processing Units and the GeForce GT 640 has 384. However, the actual shader performance of the HD 4670 is 168 and the actual shader performance of the GeForce GT 640 is 346. The GeForce GT 640 having 178 better shader performance and an altogether better performance when taking into account other relevant data means that the GeForce GT 640 delivers a marginally smoother and more efficient experience when processing graphical data than the HD 4670.

The GeForce GT 640 transistor size technology is 27 nm (nanometers) smaller than the HD 4670. This means that the GeForce GT 640 is expected to run slightly cooler and achieve higher clock frequencies than the HD 4670.

The Radeon HD 4670 1GB requires 59 Watts to run and the GeForce GT 640 requires 65 Watts. We would recommend a PSU with at least 400 Watts for the HD 4670 and a PSU with at least 350 Watts for the GeForce GT 640. The GeForce GT 640 requires 6 Watts more than the HD 4670 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 4670.