In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 980MX 8GB are massively better than the AMD Radeon HD 8850M.

The GTX 980MX has a 413 MHz higher core clock speed and 64 more Texture Mapping Units than the Radeon HD 8850M. This results in the GTX 980MX providing 83 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 GTX 980MX has a 413 MHz higher core clock speed and 48 more Render Output Units than the Radeon HD 8850M. This results in the GTX 980MX providing 56.4 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 GTX 980MX was released over three years more recently than the Radeon HD 8850M, and so the GTX 980MX is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the Radeon HD 8850M when running the latest games.

The GTX 980MX has 6144 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 980MX also has superior memory performance overall.

The GTX 980MX has 128.4 GB/sec greater memory bandwidth than the Radeon HD 8850M, which means that the memory performance of the GTX 980MX is massively better than the Radeon HD 8850M.

The GeForce GTX 980MX 8GB has 1664 Shader Processing Units and the Radeon HD 8850M has 640. However, the actual shader performance of the GTX 980MX is 2534 and the actual shader performance of the Radeon HD 8850M is 496. The GTX 980MX having 2038 better shader performance and an altogether better performance when taking into account other relevant data means that the GTX 980MX delivers a massively smoother and more efficient experience when processing graphical data than the Radeon HD 8850M.

The GeForce GTX 980MX 8GB requires 122 Watts to run and the Radeon HD 8850M requires 45 Watts. The GTX 980MX requires 77 Watts more than the Radeon HD 8850M to run. The difference is significant enough that the GTX 980MX may have an adverse affect on your yearly electricity bills in comparison to the Radeon HD 8850M.