Compare any two graphics cards:
Radeon HD 6990 vs Radeon HD 7970
IntroThe Radeon HD 6990 makes use of a 40 nm design. AMD has clocked the core frequency at 830 MHz. The GDDR5 RAM runs at a frequency of 1250 MHz on this particular card. It features 1536 SPUs along with 96 TAUs and 32 Rasterization Operator Units.
Compare those specifications to the Radeon HD 7970, which features core speeds of 925 MHz on the GPU, and 1375 MHz on the 3072 MB of GDDR5 RAM. It features 2048 SPUs along with 128 Texture Address Units and 32 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 6990, in theory, should be a lot faster than the Radeon HD 7970 overall. (explain)
Texel RateThe Radeon HD 6990 is much (more or less 35%) more effective at texture filtering than the Radeon HD 7970. (explain)
Pixel RateThe Radeon HD 6990 should be a lot (approximately 79%) faster with regards to full screen anti-aliasing than the Radeon HD 7970, and will be able to handle higher resolutions more effectively. (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 megabytes per second) that can be transferred over the external memory interface in a second. It's worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR type RAM, it must 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 higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better this number, the better the video 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 most pixels the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.