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 GT 445M v2.

The GT 445M has a 20 MHz higher core clock speed than the Radeon HD, but the Radeon HD has 16 more Texture Mapping Units than the GT 445M. As a result, the Radeon HD exhibits a 8.3 GTexel/s better Texture Fill Rate than the GT 445M. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The GT 445M has a 20 MHz higher core clock speed than the Radeon HD and the same number of Render Output Units. This results in the GT 445M providing 0.3 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 GT 445M was released over a year more recently than the Radeon HD, and so the GT 445M is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the Radeon HD.

The Radeon HD has 1024 MB more video memory than the GT 445M, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the Radeon HD also has superior memory performance overall.

The Radeon HD has 139.2 GB/sec greater memory bandwidth than the GT 445M, which means that the memory performance of the Radeon HD is massively better than the GT 445M.

The GeForce GT 445M v2 has 144 Shader Processing Units and the Mobility Radeon HD 4870 x2 has 1600. However, the actual shader performance of the GT 445M is 164 and the actual shader performance of the Radeon HD is 572. The Radeon HD having 408 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 GT 445M.

The GT 445M transistor size technology is 15 nm (nanometers) smaller than the Radeon HD. This means that the GT 445M is expected to run slightly cooler and achieve higher clock frequencies than the Radeon HD. While they exhibit similar graphical performance, the GT 445M should consume less power than the Radeon HD.

The GeForce GT 445M v2 requires 35 Watts to run and the Mobility Radeon HD 4870 x2 requires 130 Watts. The Radeon HD requires 95 Watts more than the GT 445M 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 GT 445M.