Radeon HD 4870 X2 vs Radeon HD 6950

Intro

Compare those specifications to the Radeon HD 6950, which comes with a clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It features 1408 SPUs, 88 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6950		200 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 150 Watts (75%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 should be quite a bit faster than the Radeon HD 6950 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6950		160000 MB/sec
	Difference: 70400 (44%)

Texel Rate

The Radeon HD 6950 will be a bit (more or less 17%) faster with regards to texture filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 6950		70400 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 10400 (17%)

Pixel Rate

The Radeon HD 6950 should be a little bit (about 7%) better at FSAA than the Radeon HD 4870 X2, and will be able to handle higher resolutions better. (explain)

Radeon HD 6950		25600 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 1600 (7%)

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 largest amount of information (in units of megabytes per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of 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 per second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.