Compare any two graphics cards:
GeForce 8800 GT 1GB vs GeForce 9800 GT 512MB
IntroThe GeForce 8800 GT 1GB features clock speeds of 600 MHz on the GPU, and 900 MHz on the 1024 MB of GDDR3 RAM. It features 112 SPUs along with 56 Texture Address Units and 16 Rasterization Operator Units.
Compare those specs to the GeForce 9800 GT 512MB, which makes use of a 65/55 nm design. nVidia has clocked the core frequency at 600 MHz. The GDDR3 RAM works at a speed of 900 MHz on this card. It features 112 SPUs along with 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 fill rate, so theoretically they should be equally good at at AF. (explain)
Pixel RateBoth cards have exactly the same pixel fill rate, so theoretically they should perform equally good at at anti-aliasing, 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: Bandwidth is the maximum amount of information (counted in megabytes per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one 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 video 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 maximum amount of pixels that the graphics chip could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.