Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 features a core clock speed of 900 MHz and a DDR3 memory speed of 1782 MHz. It also uses a 128-bit memory bus, and uses a 28 nm design. It is comprised of 384 SPUs, 32 Texture Address Units, and 16 ROPs.
Compare all of that to the GeForce GTX 660 Ti, which features a GPU core clock speed of 915 MHz, and 2048 MB of GDDR5 memory running at 1500 MHz through a 192-bit bus. It also is made up of 1344 SPUs, 112 TAUs, and 24 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 660 Ti should perform a lot faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 660 Ti will be much (about 256%) better at AF than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with a high resolution is important to you, then the GeForce GTX 660 Ti is a better choice, by a large margin. (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 megabytes per second) that can be moved over the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This is calculated by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called 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 bandwidth is, the lower the ability to reach the maximum fill rate.