Compare any two graphics cards:
GeForce 8600 GT 1GB DDR2 vs GeForce 8600 GT 256MB DDR2
IntroThe GeForce 8600 GT 1GB DDR2 makes use of a 80 nm design. nVidia has clocked the core speed at 540 MHz. The DDR2 RAM works at a frequency of 400 MHz on this model. It features 32 SPUs as well as 16 Texture Address Units and 8 Rasterization Operator Units.
Compare those specifications to the GeForce 8600 GT 256MB DDR2, which comes with core speeds of 540 MHz on the GPU, and 400 MHz on the 256 MB of DDR2 RAM. It features 32 SPUs along with 16 Texture Address Units and 8 ROPs.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have the exact same memory bandwidth, so in theory they should have the same performance. (explain)
Texel RateBoth cards have the exact same texel rate, so theoretically they should be equally good at at AF. (explain)
Pixel RateBoth cards have the exact same pixel fill rate, so in theory they should perform equally good at at FSAA, and be able to handle the same screen 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: Bandwidth is the largest amount of information (counted in megabytes per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.