Radeon HD 3870 X2 1GB vs Radeon HD 6950 2GB

Intro

Compare that to the Radeon HD 6950 2GB, which has clock speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1408 SPUs along with 88 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 6950 2GB, in theory, should be just a bit faster than the Radeon HD 3870 X2 1GB overall. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 15872 (11%)

Texel Rate

The Radeon HD 6950 2GB should be quite a bit (about 167%) more effective at AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 44000 (167%)

Pixel Rate

The Radeon HD 3870 X2 1GB will be a small bit (more or less 3%) better at anti-aliasing than the Radeon HD 6950 2GB, and also able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 1GB		26400 Mpixels/sec
Radeon HD 6950 2GB		25600 Mpixels/sec
	Difference: 800 (3%)

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 largest amount of data (counted in MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 applied in one second. This number is calculated by multiplying the total number of texture units by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the card's clock speed. 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 rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.