Compare any two graphics cards:
Radeon HD 4850 512MB vs Radeon HD 6850
IntroThe Radeon HD 4850 512MB comes with a core clock frequency of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
Compare all that to the Radeon HD 6850, which uses a 40 nm design. AMD has set the core frequency at 775 MHz. The GDDR5 RAM runs at a frequency of 1000 MHz on this particular model. It features 960 SPUs as well as 48 Texture Address Units and 32 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 6850 should perform much faster than the Radeon HD 4850 512MB overall. (explain)
Texel RateThe Radeon HD 6850 should be quite a bit (about 49%) faster with regards to texture filtering than the Radeon HD 4850 512MB. (explain)
Pixel RateIf running with high levels of AA is important to you, then the Radeon HD 6850 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 largest amount of information (in units of MB per second) that can be transferred past the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out 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 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 potential to reach the max fill rate.