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 RAM runs at 900 MHz through a 256-bit bus. It also is made up of 112 Stream Processors, 56 TAUs, and 16 ROPs.
Compare all that to the GeForce 9800 GT 512MB, which features core speeds of 600 MHz on the GPU, and 900 MHz on the 512 MB of GDDR3 RAM. It features 112 SPUs along with 56 Texture Address Units and 16 ROPs.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have exactly the same bandwidth, so theoretically they should have identical performance. (explain)
Texel RateBoth cards have the exact same texel rate, so in theory they should be equally good at at anisotropic filtering. (explain)
Pixel RateBoth cards have exactly the same pixel 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 maximum amount of information (measured in megabytes per second) that can be moved across the external memory interface within a second. It's worked out by multiplying the bus width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster 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 figure is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.
Pixel Rate: Pixel rate is the most pixels the graphics card can 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 colour ROPs 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 of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.