Compare any two graphics cards:
GeForce 8600 GT 1GB DDR2 vs GeForce 8600 GT 512MB DDR2
IntroThe GeForce 8600 GT 1GB DDR2 has a clock frequency of 540 MHz and a DDR2 memory speed of 400 MHz. It also uses a 128-bit bus, and uses a 80 nm design. It is comprised of 32 SPUs, 16 Texture Address Units, and 8 Raster Operation Units.
Compare those specifications to the GeForce 8600 GT 512MB DDR2, which uses a 80 nm design. nVidia has set the core speed at 540 MHz. The DDR2 memory works at a speed of 400 MHz on this specific model. It features 32 SPUs along with 16 Texture Address Units and 8 Rasterization Operator Units.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have the exact same bandwidth, so in theory they should have the same performance. (explain)
Texel RateBoth cards have exactly the same texel fill rate, so in theory they should perform equally good at at AF. (explain)
Pixel RateBoth cards have the exact same pixel fill rate, so theoretically they should be equally good at at AA, and be able to handle the same resolutions. (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.
Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.
Memory Bandwidth: Memory bandwidth is the largest amount of information (counted in MB per second) that can be transferred past the external memory interface within a second. It's worked out by multiplying the interface width by its memory clock speed. If it uses DDR RAM, it must 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 AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The higher 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 amount of pixels the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.