In terms of overall gaming performance, the graphical capabilities of the AMD Radeon HD 4650 1GB are significantly better than the Nvidia GeForce 8600 GT 512MB GDDR3.

The HD 4650 has a 60 MHz higher core clock speed and 16 more Texture Mapping Units than the 8600 GT. This results in the HD 4650 providing 10.6 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 HD 4650 has a 60 MHz higher core clock speed than the 8600 GT and the same number of Render Output Units. This results in the HD 4650 providing 0.5 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 HD 4650 was released over a year more recently than the 8600 GT, and so the HD 4650 is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the 8600 GT.

The HD 4650 has 512 MB more video memory than the 8600 GT, so is likely to be much better at displaying game textures at higher resolutions. However, the overall memory performance is about the same.

The memory bandwidth of the GeForce 8600 GT 512MB GDDR3 and the Radeon HD 4650 1GB are the same, which means the 8600 GT and the HD 4650 have equal limitations when it comes to graphical data transfer.

The GeForce 8600 GT 512MB GDDR3 has 32 Shader Processing Units and the Radeon HD 4650 1GB has 320. However, the actual shader performance of the 8600 GT is 43 and the actual shader performance of the HD 4650 is 134. The HD 4650 having 91 better shader performance and an altogether better performance when taking into account other relevant data means that the HD 4650 delivers a marginally smoother and more efficient experience when processing graphical data than the 8600 GT.

The HD 4650 transistor size technology is 25 nm (nanometers) smaller than the 8600 GT. This means that the HD 4650 is expected to run slightly cooler and achieve higher clock frequencies than the 8600 GT.

The GeForce 8600 GT 512MB GDDR3 requires 46 Watts to run and the Radeon HD 4650 1GB requires 48 Watts. We would recommend a PSU with at least 350 Watts for the 8600 GT and a PSU with at least 400 Watts for the HD 4650. The HD 4650 requires 2 Watts more than the 8600 GT to run. The difference is not significant enough for the HD 4650 to have a noticeably larger impact on your yearly electricity bills than the 8600 GT.