Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 260
IntroThe GeForce GT 640 DDR3 comes with a GPU core speed of 900 MHz, and the 2048 MB of DDR3 memory runs at 1782 MHz through a 128-bit bus. It also features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Compare that to the GeForce GTX 260, which comes with a clock frequency of 576 MHz and a GDDR3 memory speed of 999 MHz. It also makes use of a 448-bit bus, and makes use of a 65 nm design. It is comprised of 192 SPUs, 64 TAUs, and 28 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the GeForce GTX 260 should perform a lot faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 260 is a lot (approximately 28%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GTX 260 should be a little bit (approximately 12%) faster with regards to anti-aliasing than the GeForce GT 640 DDR3, and also 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: Bandwidth is the max amount of data (in units of MB per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, 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 per second. This is worked out by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core 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 many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.