Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660
IntroThe GeForce GT 640 DDR3 makes use of a 28 nm design. nVidia has clocked the core frequency at 900 MHz. The DDR3 memory runs at a frequency of 1782 MHz on this model. It features 384 SPUs along with 32 TAUs and 16 ROPs.
Compare those specifications to the GeForce GTX 660, which uses a 28 nm design. nVidia has set the core frequency at 980 MHz. The GDDR5 memory works at a speed of 1502 MHz on this specific model. It features 960 SPUs along with 80 TAUs and 24 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 660 should in theory be much faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 660 is quite a bit (more or less 172%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the GeForce GTX 660 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.
Price ComparisonPlease note that the price comparisons are based on search keywords, and might not be the exact same card listed on this page. We have no control over the accuracy of their search results.
Memory Bandwidth: Bandwidth is the maximum amount of information (in units of MB per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better 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 applied in one second. This figure is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the 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 number of pixels the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.