Compare any two graphics cards:
Radeon HD 4870 512MB vs Radeon HD 7850
IntroThe Radeon HD 4870 512MB comes with a GPU clock speed of 750 MHz, and the 512 MB of GDDR5 memory is set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
Compare all of that to the Radeon HD 7850, which has core clock speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1024 SPUs along with 64 TAUs and 32 Rasterization Operator Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 7850 should be much faster than the Radeon HD 4870 512MB overall. (explain)
Texel RateThe Radeon HD 7850 is quite a bit (more or less 83%) better at AF than the Radeon HD 4870 512MB. (explain)
Pixel RateIf running with lots of anti-aliasing is important to you, then the Radeon HD 7850 is a better choice, by a large margin. (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 MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better 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 amount of texture map elements (texels) that are processed per second. This number is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the 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 can possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the core clock speed. 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, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.