Compare any two graphics cards:
GeForce GTX 470 vs Radeon HD 4850 X2 512MB
IntroThe GeForce GTX 470 has clock speeds of 607 MHz on the GPU, and 837 MHz on the 1280 MB of GDDR5 RAM. It features 448 SPUs as well as 56 Texture Address Units and 40 Rasterization Operator Units.
Compare that to the Radeon HD 4850 X2 512MB, which comes with a clock speed of 625 MHz and a GDDR3 memory frequency of 993 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 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 470 should be 5% quicker than the Radeon HD 4850 X2 512MB overall, because of its higher data rate. (explain)
Texel RateThe Radeon HD 4850 X2 512MB should be much (more or less 47%) more effective at AF than the GeForce GTX 470. (explain)
Pixel RateIf running with lots of anti-aliasing is important to you, then the GeForce GTX 470 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.
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: Memory bandwidth is the max amount of data (in units of megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total amount of texture units by the core 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 per second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines 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, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.