In terms of overall gaming performance, the graphical capabilities of the AMD Radeon HD 7750 Sapphire 1GB GDDR5 Edition are noticeably better than the AMD Radeon HD 4850.
The HD 7750 has a 175 MHz higher core clock speed but 8 fewer Texture Mapping Units than the Radeon HD 4850. The lower TMU count doesn't matter, though, as altogether the HD 7750 manages to provide 0.6 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 7750 has a 175 MHz higher core clock speed than the Radeon HD 4850 and the same number of Render Output Units. This results in the HD 7750 providing 2.8 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 7750 was released less than a year after the Radeon HD 4850, and so they are likely to have similar driver support for optimizing performance when running the latest games.
The HD 7750 has 512 MB more video memory than the Radeon HD 4850, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the HD 7750 also has superior memory performance overall.
The HD 7750 has 8.4 GB/sec greater memory bandwidth than the Radeon HD 4850, which means that the memory performance of the HD 7750 is marginally better than the Radeon HD 4850.
The Radeon HD 4850 has 800 Shader Processing Units and the Radeon HD 7750 Sapphire 1GB GDDR5 Edition has 512. However, the actual shader performance of the Radeon HD 4850 is 325 and the actual shader performance of the HD 7750 is 348. The HD 7750 having 23 better shader performance and an altogether better performance when taking into account other relevant data means that the HD 7750 delivers a slightly smoother and more efficient experience when processing graphical data than the Radeon HD 4850.
The HD 7750 transistor size technology is 27 nm (nanometers) smaller than the Radeon HD 4850. This means that the HD 7750 is expected to run slightly cooler and achieve higher clock frequencies than the Radeon HD 4850.
The Radeon HD 4850 requires 110 Watts to run and the Radeon HD 7750 Sapphire 1GB GDDR5 Edition requires 55 Watts. We would recommend a PSU with at least 450 Watts for the Radeon HD 4850 and a PSU with at least 400 Watts for the HD 7750. The Radeon HD 4850 requires 55 Watts more than the HD 7750 to run. The difference is significant enough that the Radeon HD 4850 may have an adverse affect on your yearly electricity bills in comparison to the HD 7750.