Compare any two graphics cards:
GeForce 8600 GT 256MB DDR2 vs GeForce GTX 470
IntroThe GeForce 8600 GT 256MB DDR2 makes use of a 80 nm design. nVidia has clocked the core frequency at 540 MHz. The DDR2 RAM is set to run at a speed of 400 MHz on this specific card. It features 32 SPUs as well as 16 Texture Address Units and 8 Rasterization Operator Units.
Compare those specs to the GeForce GTX 470, which makes use of a 40 nm design. nVidia has set the core speed at 607 MHz. The GDDR5 RAM runs at a frequency of 837 MHz on this particular card. It features 448 SPUs along with 56 TAUs and 40 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically, the GeForce GTX 470 should perform much faster than the GeForce 8600 GT 256MB DDR2 in general. (explain)
Texel RateThe GeForce GTX 470 is quite a bit (approximately 293%) better at anisotropic filtering than the GeForce 8600 GT 256MB DDR2. (explain)
Pixel RateThe GeForce GTX 470 will be much (about 462%) faster with regards to anti-aliasing than the GeForce 8600 GT 256MB DDR2, and also should be able to handle higher screen resolutions more effectively. (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.
Memory Bandwidth: Bandwidth is the max amount of data (in units of megabytes per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.