Compare any two graphics cards:
Radeon HD 6990 vs Radeon HD 7970
IntroThe Radeon HD 6990 has core speeds of 830 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 memory. It features 1536 SPUs along with 96 Texture Address Units and 32 Rasterization Operator Units.
Compare all that to the Radeon HD 7970, which features a core clock speed of 925 MHz and a GDDR5 memory speed of 1375 MHz. It also makes use of a 384-bit memory bus, and makes use of a 28 nm design. It is made up of 2048 SPUs, 128 Texture Address Units, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 6990, in theory, should perform a lot faster than the Radeon HD 7970 in general. (explain)
Texel RateThe Radeon HD 6990 should be a lot (more or less 35%) better at anisotropic filtering than the Radeon HD 7970. (explain)
Pixel RateThe Radeon HD 6990 is a lot (about 79%) more effective at AA than the Radeon HD 7970, and should be capable of handling higher resolutions while still performing well. (explain)
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.
Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.
Memory Bandwidth: Bandwidth is the largest amount of information (in units of MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type memory, it should be multiplied by 2 once 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 AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.