Compare any two graphics cards:
GeForce 8800 GT 512MB vs GeForce 9800 GT 512MB
IntroThe GeForce 8800 GT 512MB features clock speeds of 600 MHz on the GPU, and 900 MHz on the 512 MB of GDDR3 memory. It features 112 SPUs as well as 56 TAUs and 16 ROPs.
Compare those specifications to the GeForce 9800 GT 512MB, which uses a 65/55 nm design. nVidia has clocked the core frequency at 600 MHz. The GDDR3 RAM is set to run at a frequency of 900 MHz on this particular card. It features 112 SPUs along with 56 TAUs and 16 Rasterization Operator Units.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have exactly the same bandwidth, so theoretically they should perform exactly the same. (explain)
Texel RateBoth cards have exactly the same texel rate, so theoretically they should perform equally good at at anisotropic filtering. (explain)
Pixel RateBoth cards have exactly the same pixel rate, so theoretically they should perform equally good at at anti-aliasing, 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: Memory bandwidth is the maximum amount of information (counted in MB per second) that can be transported across the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, 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 applied 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 the texel rate, the better the video card will be at 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 chip can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. 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 lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.