Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 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 memory bus, and makes use of a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Compare all that to the GeForce GTX 660 Ti, which features a core clock frequency of 915 MHz and a GDDR5 memory frequency of 1500 MHz. It also uses a 192-bit bus, and uses a 28 nm design. It features 1344 SPUs, 112 TAUs, and 24 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GTX 660 Ti should be quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 660 Ti should be much (approximately 256%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with lots of anti-aliasing is important to you, then the GeForce GTX 660 Ti is the winner, 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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be moved over the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This number is worked out by multiplying the total number of 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 processed in one second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. 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.