Radeon HD 4870 X2 vs Radeon HD 6950 2GB

Intro

Compare all that to the Radeon HD 6950 2GB, which uses a 40 nm design. AMD has clocked the core frequency at 800 MHz. The GDDR5 RAM works at a frequency of 1250 MHz on this card. It features 1408 SPUs as well as 88 Texture Address Units 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

In theory, the Radeon HD 4870 X2 should be quite a bit faster than the Radeon HD 6950 2GB in general. (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 will be a little bit (more or less 17%) more effective at texture 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

The Radeon HD 6950 2GB will be a small bit (about 7%) faster with regards to full screen anti-aliasing than the Radeon HD 4870 X2, and able to handle higher resolutions while still performing well. (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: Memory bandwidth is the largest amount of information (counted in megabytes per second) that can be transported over the external memory interface in one second. The number is worked out by multiplying the bus width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core clock speed. 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, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.