Compare any two graphics cards:
Radeon HD 4870 512MB vs Radeon HD 7850
IntroThe Radeon HD 4870 512MB comes with a core clock speed of 750 MHz and a GDDR5 memory speed of 900 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.
Compare those specifications to the Radeon HD 7850, which features a clock speed of 860 MHz and a GDDR5 memory speed of 1200 MHz. It also features a 256-bit bus, and makes use of a 28 nm design. It features 1024 SPUs, 64 Texture Address Units, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 7850, in theory, should perform quite a bit faster than the Radeon HD 4870 512MB in general. (explain)
Texel RateThe Radeon HD 7850 will be much (about 83%) better at texture filtering than the Radeon HD 4870 512MB. (explain)
Pixel RateThe Radeon HD 7850 will be a lot (about 129%) faster with regards to FSAA than the Radeon HD 4870 512MB, and also should be able to handle higher resolutions without slowing down too much. (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 largest amount of data (in units of MB per second) that can be transported across the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's 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 amount of texture map elements (texels) that can be applied per second. This is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.
Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.