Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 features a clock speed of 900 MHz and a DDR3 memory speed of 1782 MHz. It also uses a 128-bit memory bus, and makes use of a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 ROPs.
Compare all that to the GeForce GTX 660 Ti, which makes use of a 28 nm design. nVidia has set the core speed at 915 MHz. The GDDR5 RAM runs at a speed of 1500 MHz on this particular card. It features 1344 SPUs along with 112 TAUs and 24 Rasterization Operator Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 660 Ti should theoretically be much faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 660 Ti should be much (approximately 256%) better at texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GTX 660 Ti will be much (approximately 53%) better at anti-aliasing than the GeForce GT 640 DDR3, and will be capable of handling higher screen resolutions more effectively. (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 max amount of information (counted in MB per second) that can be transferred across the external memory interface within a second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.