In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTS 250 Zotac ECO 1GB Edition are very slightly 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 a year more recently than the GTS 250, 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 GTS 250.

The GeForce GT 640 has 1024 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 35.5 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 GT 640 has 384 Shader Processing Units and the GeForce GTS 250 Zotac ECO 1GB Edition has 128. However, the actual shader performance of the GeForce GT 640 is 346 and the actual shader performance of the GTS 250 is 216. 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 27 nm (nanometers) smaller than the GTS 250. This means that the GeForce GT 640 is expected to run slightly cooler and achieve higher clock frequencies than the GTS 250.

The GeForce GT 640 requires 65 Watts to run and the GeForce GTS 250 Zotac ECO 1GB Edition requires 125 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 GTS 250. The GTS 250 requires 60 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.