Compare any two graphics cards:
GeForce 8500 GT vs GeForce GT 640 DDR3
IntroThe GeForce 8500 GT comes with a clock frequency of 450 MHz and a DDR2 memory speed of 400 MHz. It also makes use of a 128-bit bus, and makes use of a 80 nm design. It is made up of 16 SPUs, 8 TAUs, and 4 ROPs.
Compare those specifications to the GeForce GT 640 DDR3, which comes with GPU core speed of 900 MHz, and 2048 MB of DDR3 RAM set to run at 1782 MHz through a 128-bit bus. It also features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GT 640 DDR3 should be quite a bit faster than the GeForce 8500 GT in general. (explain)
Texel RateThe GeForce GT 640 DDR3 will be much (about 700%) better at texture filtering than the GeForce 8500 GT. (explain)
Pixel RateIf running with lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is the winner, by far. (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 MB per second) that can be moved across the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 amount of texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total amount of 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 in one second.
Pixel Rate: Pixel rate is the most pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.