Compare any two graphics cards:
GeForce GTX 470 vs Radeon HD 4850 X2 512MB
IntroThe GeForce GTX 470 has a GPU clock speed of 607 MHz, and the 1280 MB of GDDR5 RAM runs at 837 MHz through a 320-bit bus. It also is made up of 448 Stream Processors, 56 TAUs, and 40 Raster Operation Units.
Compare those specs to the Radeon HD 4850 X2 512MB, which makes use of a 55 nm design. AMD has set the core frequency at 625 MHz. The GDDR3 RAM runs at a speed of 993 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 470 should theoretically be a small bit faster than the Radeon HD 4850 X2 512MB in general. (explain)
Texel RateThe Radeon HD 4850 X2 512MB will be a lot (more or less 47%) better at AF than the GeForce GTX 470. (explain)
Pixel RateThe GeForce GTX 470 is a lot (approximately 21%) more effective at AA than the Radeon HD 4850 X2 512MB, and will be able to handle higher screen 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.
One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.
Memory Bandwidth: Bandwidth is the largest amount of information (measured in MB per second) that can be transferred across the external memory interface in a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units 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 processed in a second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.