Radeon HD 6990 vs Radeon HD 7950 3GB

Intro

Compare all that to the Radeon HD 7950 3GB, which comes with clock speeds of 800 MHz on the GPU, and 1250 MHz on the 3072 MB of GDDR5 memory. It features 1792 SPUs as well as 112 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 7950 3GB		200 Watts
Radeon HD 6990		375 Watts
	Difference: 175 Watts (88%)

Memory Bandwidth

The Radeon HD 6990, in theory, should perform a lot faster than the Radeon HD 7950 3GB overall. (explain)

Radeon HD 6990		320000 MB/sec
Radeon HD 7950 3GB		240000 MB/sec
	Difference: 80000 (33%)

Texel Rate

The Radeon HD 6990 will be quite a bit (approximately 78%) better at anisotropic filtering than the Radeon HD 7950 3GB. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon HD 7950 3GB		89600 Mtexels/sec
	Difference: 69760 (78%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 6990 is superior to the Radeon HD 7950 3GB, and very much so. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon HD 7950 3GB		25600 Mpixels/sec
	Difference: 27520 (108%)

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 maximum amount of information (in units of MB per second) that can be transported past the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to the 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 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 rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.