Radeon HD 3870 X2 1GB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which comes with a core clock frequency of 775 MHz and a GDDR5 memory frequency of 1000 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It is made up of 960 SPUs, 48 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 3870 X2 1GB will be 13% quicker than the Radeon HD 6850 overall, due to its greater data rate. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon HD 6850		128000 MB/sec
	Difference: 16128 (13%)

Texel Rate

The Radeon HD 6850 should be a lot (more or less 41%) faster with regards to texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 10800 (41%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 3870 X2 1GB is the winner, though not by far. (explain)

Radeon HD 3870 X2 1GB		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: Bandwidth is the max amount of information (measured in megabytes per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.