Radeon HD 6990 vs Radeon HD 7950 3GB

Intro

Compare those specifications to the Radeon HD 7950 3GB, which has a core clock speed of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also makes use of a 384-bit memory bus, and uses a 28 nm design. It is made up of 1792 SPUs, 112 TAUs, and 32 ROPs.

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

Theoretically speaking, the Radeon HD 6990 will be 33% quicker than the Radeon HD 7950 3GB overall, due to its greater bandwidth. (explain)

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

Texel Rate

The Radeon HD 6990 is a lot (more or less 78%) faster with regards to texture 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

The Radeon HD 6990 is quite a bit (approximately 108%) faster with regards to AA than the Radeon HD 7950 3GB, and also able to handle higher screen resolutions while still performing well. (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 data (measured in megabytes per second) that can be transferred over the external memory interface in one second. It's calculated by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.