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 speed at 830 MHz. The GDDR5 memory runs at a frequency of 1250 MHz on this particular card. It features 1536 SPUs along with 96 TAUs and 32 ROPs.
Compare those specs to the Radeon HD 7970, which has a clock speed of 925 MHz and a GDDR5 memory frequency of 1375 MHz. It also makes use of a 384-bit memory bus, and uses 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)
As far as performance goes, the Radeon HD 6990 should theoretically be much better than the Radeon HD 7970 in general. (explain)
Texel RateThe Radeon HD 6990 should be a lot (more or less 35%) better at AF than the Radeon HD 7970. (explain)
Pixel RateThe Radeon HD 6990 will be a lot (more or less 79%) faster with regards to full screen anti-aliasing than the Radeon HD 7970, and also will be capable of handling higher screen 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 maximum amount of information (measured in megabytes per second) that can be transferred across the external memory interface within a second. The number is 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 better the memory bandwidth, the better 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 can be applied per second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.
Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called 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 potential to reach the max fill rate.