Compare any two graphics cards:
Radeon HD 4790 vs Radeon HD 6950
IntroThe Radeon HD 4790 features a GPU core speed of 600 MHz, and the 512 MB of GDDR5 memory runs at 800 MHz through a 256-bit bus. It also is made up of 640(128x5) SPUs, 32 TAUs, and 16 ROPs.
Compare those specifications to the Radeon HD 6950, which comes with a clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also uses a 256-bit memory bus, and uses a 40 nm design. It is comprised of 1408 SPUs, 88 Texture Address Units, and 32 ROPs.
Power Usage and Theoretical Benchmarks
Theoretically speaking, the Radeon HD 6950 is 56% quicker than the Radeon HD 4790 overall, because of its greater bandwidth. (explain)
Texel RateThe Radeon HD 6950 is much (more or less 267%) more effective at AF than the Radeon HD 4790. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the Radeon HD 6950 is the winner, and very much so. (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.
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 information (counted in megabytes per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the interface width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.