Compare any two graphics cards:
GeForce GTX 285 1GB vs Radeon HD 6970
IntroThe GeForce GTX 285 1GB comes with clock speeds of 648 MHz on the GPU, and 1242 MHz on the 1024 MB of GDDR3 RAM. It features 240 SPUs along with 80 TAUs and 32 ROPs.
Compare all of that to the Radeon HD 6970, which comes with clock speeds of 880 MHz on the GPU, and 1375 MHz on the 2048 MB of GDDR5 RAM. It features 1536 SPUs as well as 96 Texture Address Units and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically, the Radeon HD 6970 should perform a little bit faster than the GeForce GTX 285 1GB overall. (explain)
Texel RateThe Radeon HD 6970 should be a lot (more or less 63%) more effective at AF than the GeForce GTX 285 1GB. (explain)
Pixel RateThe Radeon HD 6970 will be a lot (about 36%) better at anti-aliasing than the GeForce GTX 285 1GB, and capable of handling higher resolutions while still performing well. (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: Memory bandwidth is the largest amount of information (in units of megabytes per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This figure is calculated by multiplying the total number of texture units of the card 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 the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.