Compare any two graphics cards:
GeForce 8600 GT 1GB DDR2 vs Radeon HD 4550 512MB
IntroThe GeForce 8600 GT 1GB DDR2 has a GPU clock speed of 540 MHz, and the 1024 MB of DDR2 RAM runs at 400 MHz through a 128-bit bus. It also features 32 SPUs, 16 Texture Address Units, and 8 ROPs.
Compare those specs to the Radeon HD 4550 512MB, which comes with core speeds of 600 MHz on the GPU, and 800 MHz on the 512 MB of GDDR3 RAM. It features 80(16x5) SPUs as well as 8 TAUs and 4 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Both cards have exactly the same memory bandwidth, so theoretically they should have the same performance. (explain)
Texel RateThe GeForce 8600 GT 1GB DDR2 is quite a bit (more or less 80%) more effective at anisotropic filtering than the Radeon HD 4550 512MB. (explain)
Pixel RateIf using high levels of AA is important to you, then the GeForce 8600 GT 1GB DDR2 is superior to the Radeon HD 4550 512MB, 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.
Memory Bandwidth: Memory bandwidth is the maximum amount of data (counted in MB per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. 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 amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total number of texture units by the core clock 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 processed in a second.
Pixel Rate: Pixel rate is the most pixels the graphics card can 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 colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.