Compare any two graphics cards:
Radeon HD 6790 vs Radeon HD 6870
IntroThe Radeon HD 6790 has a GPU clock speed of 840 MHz, and the 1024 MB of GDDR5 memory runs at 1050 MHz through a 256-bit bus. It also features 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.
Compare those specifications to the Radeon HD 6870, which features a core clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also makes use of a 256-bit bus, and makes use of a 40 nm design. It features 1120 SPUs, 56 TAUs, and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Both cards have the exact same bandwidth, so in theory they should have identical performance. (explain)
Texel RateThe Radeon HD 6870 should be a lot (more or less 50%) faster with regards to anisotropic filtering than the Radeon HD 6790. (explain)
Pixel RateThe Radeon HD 6870 is much (more or less 114%) better at AA than the Radeon HD 6790, and also will be able to handle higher screen 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.
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 data (counted in megabytes per second) that can be transported over the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. 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 texture map elements (texels) that are applied in one 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.