In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTS 250 v2 are noticeably better than the Nvidia GeForce GT 640.

The GeForce GT 640 has a 227 MHz higher core clock speed than the GTS 250, but the GTS 250 has 32 more Texture Mapping Units than the GeForce GT 640. As a result, the GTS 250 exhibits a 14.3 GTexel/s better Texture Fill Rate than the GeForce GT 640. 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 227 MHz higher core clock speed than the GTS 250 and the same number of Render Output Units. This results in the GeForce GT 640 providing 3.6 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 GTS 250, 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 GTS 250 when running the latest games.

The GeForce GT 640 has 1536 MB more video memory than the GTS 250, so is likely to be much better at displaying game textures at higher resolutions. However, overall, the GTS 250 has superior memory performance.

The GTS 250 has 41.9 GB/sec greater memory bandwidth than the GeForce GT 640, which means that the memory performance of the GTS 250 is noticeably better than the GeForce GT 640.

The GeForce GTS 250 v2 has 128 Shader Processing Units and the GeForce GT 640 has 384. However, the actual shader performance of the GTS 250 is 216 and the actual shader performance of the GeForce GT 640 is 346. The GeForce GT 640 having 130 better shader performance is not particularly notable, as altogether the GTS 250 performs better when taking into account other relevant data.

The GeForce GT 640 transistor size technology is 37 nm (nanometers) smaller than the GTS 250. This means that the GeForce GT 640 is expected to run much cooler and achieve higher clock frequencies than the GTS 250.

The GeForce GTS 250 v2 requires 140 Watts to run and the GeForce GT 640 requires 65 Watts. We would recommend a PSU with at least 450 Watts for the GTS 250 and a PSU with at least 350 Watts for the GeForce GT 640. The GTS 250 requires 75 Watts more than the GeForce GT 640 to run. The difference is significant enough that the GTS 250 may have an adverse affect on your yearly electricity bills in comparison to the GeForce GT 640.