Compare any two graphics cards:
GeForce 8800 GT 1GB vs GeForce 9800 GT 512MB
IntroThe GeForce 8800 GT 1GB comes with a GPU core speed of 600 MHz, and the 1024 MB of GDDR3 memory runs at 900 MHz through a 256-bit bus. It also is comprised of 112 SPUs, 56 TAUs, and 16 Raster Operation Units.
Compare all of that to the GeForce 9800 GT 512MB, which features core clock speeds of 600 MHz on the GPU, and 900 MHz on the 512 MB of GDDR3 RAM. It features 112 SPUs as well as 56 TAUs and 16 ROPs.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have exactly the same bandwidth, so in theory they should have identical performance. (explain)
Texel RateBoth cards have exactly the same texel rate, so in theory they should perform equally good at at anisotropic filtering. (explain)
Pixel RateBoth cards have exactly the same pixel fill rate, so theoretically they should be equally good at at AA, and be capable of handling 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 max amount of information (in units of MB per second) that can be moved over the external memory interface in a second. It's worked out by multiplying the interface width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum amount of pixels that 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 number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.