Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 uses a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 memory works at a speed of 1782 MHz on this specific model. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.
Compare those specifications to the GeForce GTX 660 Ti, which has GPU clock speed of 915 MHz, and 2048 MB of GDDR5 memory set to run at 1500 MHz through a 192-bit bus. It also features 1344 SPUs, 112 Texture Address Units, and 24 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 660 Ti will be 153% quicker than the GeForce GT 640 DDR3 overall, due to its higher bandwidth. (explain)
Texel RateThe GeForce GTX 660 Ti will be quite a bit (more or less 256%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf using a high resolution 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 max amount of information (counted in megabytes per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the interface width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This number is worked out by multiplying the total texture units of the card by the core clock 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 processed in a second.
Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.