Compare any two graphics cards:
GeForce 8500 GT vs GeForce GT 640 DDR3
IntroThe GeForce 8500 GT uses a 80 nm design. nVidia has clocked the core speed at 450 MHz. The DDR2 memory 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 all of that to the GeForce GT 640 DDR3, which has core speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs as well as 32 TAUs and 16 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
As far as performance goes, the GeForce GT 640 DDR3 should in theory be quite a bit better than the GeForce 8500 GT in general. (explain)
Texel RateThe GeForce GT 640 DDR3 will be quite a bit (about 700%) more effective at texture filtering than the GeForce 8500 GT. (explain)
Pixel RateIf using a high resolution is important to you, then the GeForce GT 640 DDR3 is the winner, and very much so. (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 largest amount of data (measured in megabytes per second) that can be moved over the external memory interface in one second. It is worked out by multiplying the interface width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the 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 calculated by multiplying the total texture units by the core 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 maximum amount of pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.