Compare any two graphics cards:
Radeon HD 6990 vs Radeon HD 7970
IntroThe Radeon HD 6990 comes with a core clock frequency of 830 MHz and a GDDR5 memory speed of 1250 MHz. It also uses a 256-bit memory bus, and uses a 40 nm design. It features 1536 SPUs, 96 TAUs, and 32 Raster Operation Units.
Compare all of that to the Radeon HD 7970, which comes with a clock speed of 925 MHz and a GDDR5 memory frequency of 1375 MHz. It also features a 384-bit memory bus, and makes use of a 28 nm design. It is comprised of 2048 SPUs, 128 TAUs, and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 6990 should be much faster than the Radeon HD 7970 in general. (explain)
Texel RateThe Radeon HD 6990 is quite a bit (approximately 35%) better at AF than the Radeon HD 7970. (explain)
Pixel RateThe Radeon HD 6990 should be much (more or less 79%) faster with regards to full screen anti-aliasing than the Radeon HD 7970, and will be capable of handling higher resolutions without losing too much performance. (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: Memory bandwidth is the largest amount of data (measured in megabytes per second) that can be transported over the external memory interface in one second. It's worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed in one second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per 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. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. 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 ability to reach the max fill rate.