In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 580M SLI are massively better than the AMD Radeon HD 8850M.

The Radeon HD 8850M has a 5 MHz higher core clock speed than the GTX 580M, but the GTX 580M has 88 more Texture Mapping Units than the Radeon HD 8850M. As a result, the GTX 580M exhibits a 54.4 GTexel/s better Texture Fill Rate than the Radeon HD 8850M. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The Radeon HD 8850M has a 5 MHz higher core clock speed than the GTX 580M, but the GTX 580M has 48 more Render Output Units than the Radeon HD 8850M. As a result, the GTX 580M exhibits a 29.7 GPixel/s better Pixel Fill Rate than the Radeon HD 8850M. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The Radeon HD 8850M was released over a year more recently than the GTX 580M, and so the Radeon HD 8850M is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the GTX 580M.

The GTX 580M has 2048 MB more video memory than the Radeon HD 8850M, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the GTX 580M also has superior memory performance overall.

The GTX 580M has 160 GB/sec greater memory bandwidth than the Radeon HD 8850M, which means that the memory performance of the GTX 580M is massively better than the Radeon HD 8850M.

The Radeon HD 8850M has 640 Shader Processing Units and the GeForce GTX 580M SLI has 768. However, the actual shader performance of the Radeon HD 8850M is 496 and the actual shader performance of the GTX 580M is 952. The GTX 580M having 456 better shader performance and an altogether better performance when taking into account other relevant data means that the GTX 580M delivers a massively smoother and more efficient experience when processing graphical data than the Radeon HD 8850M.

The Radeon HD 8850M transistor size technology is 12 nm (nanometers) smaller than the GTX 580M. This means that the Radeon HD 8850M is expected to run slightly cooler and achieve higher clock frequencies than the GTX 580M.

The Radeon HD 8850M requires 45 Watts to run and the GeForce GTX 580M SLI requires 200 Watts. The GTX 580M requires 155 Watts more than the Radeon HD 8850M to run. The difference is significant enough that the GTX 580M may have an adverse affect on your yearly electricity bills in comparison to the Radeon HD 8850M.