Radeon HD 3870 X2 512MB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which features clock speeds of 775 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 memory. It features 960 SPUs along with 48 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 6850 should theoretically perform just a bit faster than the Radeon HD 3870 X2 512MB in general. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 6850 will be much (approximately 41%) more effective at AF than the Radeon HD 3870 X2 512MB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 10800 (41%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 3870 X2 512MB is superior to the Radeon HD 6850, not by a very large margin though. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 6850		24800 Mpixels/sec
	Difference: 1600 (6%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be moved past the external memory interface in one second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock 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, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.