In terms of overall gaming performance, the graphical capabilities of the AMD Mobility Radeon HD 4870 x2 are very slightly better than the Nvidia GeForce 920M 2GB.

The GeForce 920M 2GB has a 25 MHz higher core clock speed than the Radeon HD, but the Radeon HD has 8 more Texture Mapping Units than the GeForce 920M 2GB. As a result, the Radeon HD exhibits a 3.6 GTexel/s better Texture Fill Rate than the GeForce 920M 2GB. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The GeForce 920M 2GB has a 25 MHz higher core clock speed than the Radeon HD, but the Radeon HD has 8 more Render Output Units than the GeForce 920M 2GB. As a result, the Radeon HD exhibits a 4.2 GPixel/s better Pixel Fill Rate than the GeForce 920M 2GB. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The GeForce 920M 2GB was released over three years more recently than the Radeon HD, and so the GeForce 920M 2GB is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the Radeon HD when running the latest games.

The GeForce 920M 2GB and the Mobility Radeon HD 4870 x2 have the same amount of video memory, but are likely to provide slightly different experiences when displaying game textures at high resolutions.

The Radeon HD has 164.8 GB/sec greater memory bandwidth than the GeForce 920M 2GB, which means that the memory performance of the Radeon HD is massively better than the GeForce 920M 2GB.

The GeForce 920M 2GB has 384 Shader Processing Units and the Mobility Radeon HD 4870 x2 has 1600. However, the actual shader performance of the GeForce 920M 2GB is 366 and the actual shader performance of the Radeon HD is 572. The Radeon HD having 206 better shader performance and an altogether better performance when taking into account other relevant data means that the Radeon HD delivers a massively smoother and more efficient experience when processing graphical data than the GeForce 920M 2GB.

The GeForce 920M 2GB transistor size technology is 27 nm (nanometers) smaller than the Radeon HD. This means that the GeForce 920M 2GB is expected to run slightly cooler and achieve higher clock frequencies than the Radeon HD. While they exhibit similar graphical performance, the GeForce 920M 2GB should consume less power than the Radeon HD.

The GeForce 920M 2GB requires 25 Watts to run and the Mobility Radeon HD 4870 x2 requires 130 Watts. The Radeon HD requires 105 Watts more than the GeForce 920M 2GB to run. The difference is significant enough that the Radeon HD may have an adverse affect on your yearly electricity bills in comparison to the GeForce 920M 2GB.