Compare any two graphics cards:
GeForce GTX 285 2GB vs Radeon HD 6950
IntroThe GeForce GTX 285 2GB has a GPU core speed of 648 MHz, and the 2048 MB of GDDR3 RAM is set to run at 1242 MHz through a 512-bit bus. It also is comprised of 240 Stream Processors, 80 Texture Address Units, and 32 ROPs.
Compare all of that to the Radeon HD 6950, which features GPU core speed of 800 MHz, and 1024 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also features 1408 Stream Processors, 88 TAUs, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the Radeon HD 6950 should be just a bit faster than the GeForce GTX 285 2GB overall. (explain)
Texel RateThe Radeon HD 6950 will be much (about 36%) better at AF than the GeForce GTX 285 2GB. (explain)
Pixel RateIf using high levels of AA is important to you, then the Radeon HD 6950 is the winner, and very much so. (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 megabytes per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the bus width by the speed of its memory. In the case of DDR type RAM, it must be multiplied by 2 again. If 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 are processed in one second. This is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to its local memory in one 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 drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.