In terms of overall gaming performance, the graphical capabilities of the AMD Radeon R9 M485X 4GB are massively better than the AMD Radeon HD 8850M.

The R9 M485X has a 98 MHz higher core clock speed and 88 more Texture Mapping Units than the Radeon HD 8850M. This results in the R9 M485X providing 67.5 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 R9 M485X has a 98 MHz higher core clock speed and 16 more Render Output Units than the Radeon HD 8850M. This results in the R9 M485X providing 13.1 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 R9 M485X was released over three years more recently than the Radeon HD 8850M, and so the R9 M485X 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 R9 M485X 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 R9 M485X also has superior memory performance overall.

The R9 M485X has 128 GB/sec greater memory bandwidth than the Radeon HD 8850M, which means that the memory performance of the R9 M485X is massively better than the Radeon HD 8850M.

The Radeon R9 M485X 4GB has 2048 Shader Processing Units and the Radeon HD 8850M has 640. However, the actual shader performance of the R9 M485X is 1259 and the actual shader performance of the Radeon HD 8850M is 496. The R9 M485X having 763 better shader performance and an altogether better performance when taking into account other relevant data means that the R9 M485X delivers a massively smoother and more efficient experience when processing graphical data than the Radeon HD 8850M.

The Radeon R9 M485X 4GB requires 125 Watts to run and the Radeon HD 8850M requires 45 Watts. The R9 M485X requires 80 Watts more than the Radeon HD 8850M to run. The difference is significant enough that the R9 M485X may have an adverse affect on your yearly electricity bills in comparison to the Radeon HD 8850M.