Radeon HD 4850 2GB vs Radeon HD 7850

Intro

Compare those specifications to the Radeon HD 7850, which has a clock frequency of 860 MHz and a GDDR5 memory frequency of 1200 MHz. It also uses a 256-bit bus, and makes use of a 28 nm design. It is made up of 1024 SPUs, 64 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 7850		130 Watts
	Difference: 20 Watts (18%)

Memory Bandwidth

In theory, the Radeon HD 7850 should perform much faster than the Radeon HD 4850 2GB overall. (explain)

Radeon HD 7850		153600 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 90048 (142%)

Texel Rate

The Radeon HD 7850 will be a lot (more or less 120%) faster with regards to anisotropic filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 7850		55040 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 30040 (120%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7850 is the winner, and very much so. (explain)

Radeon HD 7850		27520 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 17520 (175%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of information (measured in MB per second) that can be transported over the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.