In terms of overall gaming performance, the graphical capabilities of the GeForce GT 640 and the Radeon HD 6670 are equal.

The GeForce GT 640 has a 102 MHz higher core clock speed and 8 more Texture Mapping Units than the Radeon HD 6670. This results in the GeForce GT 640 providing 9.7 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 102 MHz higher core clock speed and 8 more Render Output Units than the Radeon HD 6670. This results in the GeForce GT 640 providing 8 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 Radeon HD 6670, 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 Radeon HD 6670.

The GeForce GT 640 has 1024 MB more video memory than the Radeon HD 6670, so is likely to be much better at displaying game textures at higher resolutions. However, overall, the Radeon HD 6670 has superior memory performance.

The Radeon HD 6670 has 35.5 GB/sec greater memory bandwidth than the GeForce GT 640, which means that the memory performance of the Radeon HD 6670 is noticeably better than the GeForce GT 640.

The GeForce GT 640 has 384 Shader Processing Units and the Radeon HD 6670 has 480. However, the actual shader performance of the GeForce GT 640 is 346 and the actual shader performance of the Radeon HD 6670 is 192. The GeForce GT 640 having 154 better shader performance is not particularly notable, as altogether the Radeon HD 6670 performs better when taking into account other relevant data.

The GeForce GT 640 transistor size technology is 12 nm (nanometers) smaller than the Radeon HD 6670. This means that the GeForce GT 640 is expected to run slightly cooler and achieve higher clock frequencies than the Radeon HD 6670. While they exhibit similar graphical performance, the GeForce GT 640 should consume less power than the Radeon HD 6670.

The GeForce GT 640 requires 65 Watts to run and the Radeon HD 6670 requires 66 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 Radeon HD 6670. The Radeon HD 6670 requires 1 Watts more than the GeForce GT 640 to run. The difference is not significant enough for the Radeon HD 6670 to have a noticeably larger impact on your yearly electricity bills than the GeForce GT 640.