Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 660 Ti
IntroThe GeForce GT 640 DDR3 has clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs as well as 32 TAUs and 16 Rasterization Operator Units.
Compare all of that to the GeForce GTX 660 Ti, which has a core clock speed of 915 MHz and a GDDR5 memory frequency of 1500 MHz. It also uses a 192-bit memory bus, and makes use of a 28 nm design. It features 1344 SPUs, 112 Texture Address Units, and 24 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce GTX 660 Ti should in theory be much superior to the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 660 Ti is a lot (about 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 should be capable of handling higher screen resolutions better. (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 maximum amount of data (counted in MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the bus width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.