In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GT 640 are noticeably better than the Nvidia Quadro K620.

The GeForce GT 640 has a 235 MHz higher core clock speed and the same number of Texture Mapping Units as the Quadro K620. This results in the GeForce GT 640 providing 7.6 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 235 MHz higher core clock speed than the Quadro K620 and the same number of Render Output Units. This results in the GeForce GT 640 providing 3.7 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 Quadro K620 was released over a year more recently than the GeForce GT 640, and so the Quadro K620 is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the GeForce GT 640.

The GeForce GT 640 has 1024 MB more video memory than the Quadro K620, so is likely to be much better at displaying game textures at higher resolutions. However, overall, the Quadro K620 has superior memory performance.

The Quadro K620 has 0.3 GB/sec greater memory bandwidth than the GeForce GT 640, which means that the memory performance of the Quadro K620 is marginally better than the GeForce GT 640.

Both the GeForce GT 640 and the Quadro K620 have 384 Shader Processing Units. The two GPUs are based on different architectures, but deliver an equivalent shader performance. To compare, we must continue to look at the memory bandwidth, Texture and Pixel Rates. In this case, the GeForce GT 640 has 7.6 GTexel/s better Texture Fill Rate and 3.7 GPixel/s better Pixel Fill Rate, but the Quadro K620 has 0.3 GB/sec greater memory bandwidth. Although the GPUs are very similar in performance, the GeForce GT 640 takes the edge.

The GeForce GT 640 requires 65 Watts to run and the Quadro K620 requires 45 Watts. We would recommend a PSU with at least 350 Watts for the GeForce GT 640 and a PSU with at least 350 Watts for the Quadro K620. The GeForce GT 640 requires 20 Watts more than the Quadro K620 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 Quadro K620.