Compare any two graphics cards:
Radeon HD 7850 vs Radeon HD 7870
IntroThe Radeon HD 7850 uses a 28 nm design. AMD has clocked the core speed at 860 MHz. The GDDR5 RAM runs at a frequency of 1200 MHz on this model. It features 1024 SPUs as well as 64 Texture Address Units and 32 ROPs.
Compare that to the Radeon HD 7870, which features a clock speed of 1000 MHz and a GDDR5 memory frequency of 1200 MHz. It also makes use of a 256-bit bus, and uses a 28 nm design. It is comprised of 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Both cards have the exact same bandwidth, so in theory they should perform exactly the same. (explain)
Texel RateThe Radeon HD 7870 should be quite a bit (approximately 45%) faster with regards to anisotropic filtering than the Radeon HD 7850. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the Radeon HD 7870 is a better choice, but only just. (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 max amount of data (counted in megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the bus width by its memory clock speed. If the card has DDR type memory, it must 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 AA, HDR 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 better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.
Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.