Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 550 Ti
IntroThe GeForce GT 640 DDR3 comes with a clock speed of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also features a 128-bit bus, and uses a 28 nm design. It is made up of 384 SPUs, 32 TAUs, and 16 Raster Operation Units.
Compare those specifications to the GeForce GTX 550 Ti, which has a GPU core clock speed of 900 MHz, and 1024 MB of GDDR5 RAM running at 1026 MHz through a 192-bit bus. It also is comprised of 192 Stream Processors, 32 TAUs, and 24 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 550 Ti is 73% faster than the GeForce GT 640 DDR3 overall, due to its higher bandwidth. (explain)
Texel RateBoth cards have exactly the same texel fill rate, so theoretically they should perform equally good at at anisotropic filtering. (explain)
Pixel RateThe GeForce GTX 550 Ti should be a lot (more or less 50%) faster with regards to FSAA than the GeForce GT 640 DDR3, and will be capable of handling higher resolutions better. (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 information (in units of megabytes per second) that can be transferred past the external memory interface in one second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.