Compare any two graphics cards:
GeForce 9800 GT 1GB vs GeForce 9800 GT 512MB
IntroThe GeForce 9800 GT 1GB has core speeds of 600 MHz on the GPU, and 900 MHz on the 1024 MB of GDDR3 RAM. It features 112 SPUs as well as 56 TAUs and 16 Rasterization Operator Units.
Compare those specifications to the GeForce 9800 GT 512MB, which comes with GPU core speed of 600 MHz, and 512 MB of GDDR3 memory running at 900 MHz through a 256-bit bus. It also is made up of 112 Stream Processors, 56 Texture Address Units, and 16 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
Both cards have the exact same memory bandwidth, so in theory they should perform the same. (explain)
Texel RateBoth cards have exactly the same texel rate, so theoretically they should be equally good at at AF. (explain)
Pixel RateBoth cards have the exact same pixel rate, so theoretically they should be equally good at at anti-aliasing, 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: Bandwidth is the max amount of data (counted in megabytes per second) that can be moved past the external memory interface in a second. The number is calculated by multiplying the interface width by its memory clock speed. If the card has DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed in one second. This is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The higher this number, the better the card will be at 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 the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant 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.