Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 550 Ti
IntroThe GeForce GT 640 DDR3 comes with a GPU core clock speed of 900 MHz, and the 2048 MB of DDR3 RAM is set to run at 1782 MHz through a 128-bit bus. It also features 384 Stream Processors, 32 TAUs, and 16 Raster Operation Units.
Compare those specifications to the GeForce GTX 550 Ti, which makes use of a 40 nm design. nVidia has set the core speed at 900 MHz. The GDDR5 memory is set to run at a speed of 1026 MHz on this particular model. It features 192 SPUs as well as 32 TAUs and 24 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 550 Ti should be 73% faster than the GeForce GT 640 DDR3 overall, due to its greater data rate. (explain)
Texel RateBoth cards have the exact same texel fill rate, so in theory they should be equally good at at AF. (explain)
Pixel RateThe GeForce GTX 550 Ti should be quite a bit (about 50%) faster with regards to anti-aliasing than the GeForce GT 640 DDR3, and able to handle higher 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.
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 largest amount of information (counted in MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's 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 amount of texture map elements (texels) that are processed per second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs 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 output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.