Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 260
IntroThe GeForce GT 640 DDR3 uses a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 memory is set to run at a frequency of 1782 MHz on this model. It features 384 SPUs as well as 32 Texture Address Units and 16 ROPs.
Compare those specs to the GeForce GTX 260, which comes with GPU core speed of 576 MHz, and 896 MB of GDDR3 memory running at 999 MHz through a 448-bit bus. It also is made up of 192 SPUs, 64 Texture Address Units, and 28 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 260, in theory, should be a lot faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce GTX 260 should be quite a bit (more or less 28%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GTX 260 should be a small bit (about 12%) better at FSAA than the GeForce GT 640 DDR3, and also will be capable of handling higher resolutions without slowing down too much. (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 largest amount of data (in units of MB per second) that can be transferred past the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 are processed in one second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.