Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 has core clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 32 TAUs and 16 ROPs.
Compare that to the GeForce GTX 660 Ti, which has a GPU core clock speed of 915 MHz, and 2048 MB of GDDR5 RAM set to run at 1500 MHz through a 192-bit bus. It also is made up of 1344 SPUs, 112 Texture Address Units, and 24 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the GeForce GTX 660 Ti will be 153% quicker than the GeForce GT 640 DDR3 in general, due to its greater bandwidth. (explain)
Texel RateThe GeForce GTX 660 Ti will be quite a bit (about 256%) faster with regards to AF than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with high levels of AA is important to you, then the GeForce GTX 660 Ti is superior to the GeForce GT 640 DDR3, 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: Bandwidth is the maximum amount of data (in units of MB per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the interface width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher 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 number of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the graphics card will be at handling 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 per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the core 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 many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.