Compare any two graphics cards:
GeForce GTX 580 3GB vs Radeon HD 6770
IntroThe GeForce GTX 580 3GB makes use of a 40 nm design. nVidia has set the core frequency at 772 MHz. The GDDR5 memory runs at a speed of 1002 MHz on this particular model. It features 512 SPUs along with 64 TAUs and 48 Rasterization Operator Units.
Compare those specs to the Radeon HD 6770, which features core clock speeds of 900 MHz on the GPU, and 1050 MHz on the 512 MB of GDDR5 RAM. It features 800 SPUs along with 40 TAUs and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 580 3GB will be 186% faster than the Radeon HD 6770 in general, because of its greater bandwidth. (explain)
Texel RateThe GeForce GTX 580 3GB will be quite a bit (more or less 37%) better at anisotropic filtering than the Radeon HD 6770. (explain)
Pixel RateThe GeForce GTX 580 3GB is a lot (about 157%) better at anti-aliasing than the Radeon HD 6770, and should be able to handle higher screen resolutions more effectively. (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.
Memory Bandwidth: Bandwidth is the max amount of data (measured in MB per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the interface width by its memory clock speed. If the card has DDR type memory, it must be multiplied by 2 once 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 anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the 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 that the graphics chip could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.