Radeon HD 4870 X2 vs Radeon HD 6950 2GB

Intro

Compare those specs to the Radeon HD 6950 2GB, which makes use of a 40 nm design. AMD has clocked the core speed at 800 MHz. The GDDR5 memory is set to run at a frequency of 1250 MHz on this particular card. It features 1408 SPUs as well as 88 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6950 2GB		200 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 150 Watts (75%)

Memory Bandwidth

The Radeon HD 4870 X2 should in theory be quite a bit faster than the Radeon HD 6950 2GB overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6950 2GB		160000 MB/sec
	Difference: 70400 (44%)

Texel Rate

The Radeon HD 6950 2GB is just a bit (approximately 17%) faster with regards to anisotropic filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 10400 (17%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 6950 2GB is superior to the Radeon HD 4870 X2, though only just barely. (explain)

Radeon HD 6950 2GB		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 max amount of data (measured in MB per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR 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, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.