Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 460
IntroThe GeForce GT 640 DDR3 comes with a GPU core clock speed of 900 MHz, and the 2048 MB of DDR3 memory runs at 1782 MHz through a 128-bit bus. It also is made up of 384 SPUs, 32 TAUs, and 16 ROPs.
Compare all that to the GeForce GTX 460, which has a clock speed of 675 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 192-bit memory bus, and makes use of a 40 nm design. It features 336 SPUs, 56 TAUs, and 24 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GTX 460 is 52% faster than the GeForce GT 640 DDR3 overall, due to its greater bandwidth. (explain)
Texel RateThe GeForce GTX 460 is a lot (about 31%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with high levels of AA is important to you, then the GeForce GTX 460 is superior to the GeForce GT 640 DDR3, but not 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: Memory bandwidth is the maximum amount of data (counted in MB per second) that can be moved past the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at 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 can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.