Compare any two graphics cards:
GeForce 8500 GT vs GeForce GT 640 DDR3
IntroThe GeForce 8500 GT makes use of a 80 nm design. nVidia has clocked the core frequency at 450 MHz. The DDR2 RAM is set to run at a speed of 400 MHz on this particular model. It features 16 SPUs as well as 8 TAUs and 4 Rasterization Operator Units.
Compare those specs to the GeForce GT 640 DDR3, which has a clock speed of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GT 640 DDR3 should be quite a bit faster than the GeForce 8500 GT overall. (explain)
Texel RateThe GeForce GT 640 DDR3 will be much (more or less 700%) better at anisotropic filtering than the GeForce 8500 GT. (explain)
Pixel RateThe GeForce GT 640 DDR3 is a lot (more or less 700%) more effective at anti-aliasing than the GeForce 8500 GT, and also able to handle higher screen resolutions while still performing well. (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 (measured in MB per second) that can be moved over the external memory interface in a second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, the result should be multiplied by 2 once 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 AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.