Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 460
IntroThe GeForce GT 640 DDR3 comes with a GPU core speed of 900 MHz, and the 2048 MB of DDR3 RAM runs at 1782 MHz through a 128-bit bus. It also is made up of 384 Stream Processors, 32 TAUs, and 16 ROPs.
Compare all that to the GeForce GTX 460, which features a core 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 Texture Address Units, and 24 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GTX 460 should perform quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 460 will be quite a bit (more or less 31%) better at texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf using a high screen resolution is important to you, then the GeForce GTX 460 is a better choice, not by a very large margin though. (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 maximum amount of information (counted in MB per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.
Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.