Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 has a clock frequency of 900 MHz and a DDR3 memory frequency of 1782 MHz. It also makes use of a 128-bit bus, and makes use of a 28 nm design. It features 384 SPUs, 32 TAUs, and 16 ROPs.
Compare all of that to the GeForce GTX 660 Ti, which features core speeds of 915 MHz on the GPU, and 1500 MHz on the 2048 MB of GDDR5 memory. It features 1344 SPUs as well as 112 Texture Address Units 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, in theory, should be quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 660 Ti will be quite a bit (approximately 256%) better at texture filtering 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 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 max amount of information (in units of MB per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster 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 can be processed in one second. This figure is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, 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 most pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.