Compare any two graphics cards:
GeForce GT 640 DDR3 vs GeForce GTX 580 3GB
IntroThe GeForce GT 640 DDR3 makes use of a 28 nm design. nVidia has clocked the core speed at 900 MHz. The DDR3 RAM is set to run at a speed of 1782 MHz on this particular card. It features 384 SPUs along with 32 TAUs and 16 ROPs.
Compare those specs to the GeForce GTX 580 3GB, which has GPU clock speed of 772 MHz, and 3072 MB of GDDR5 memory running at 1002 MHz through a 384-bit bus. It also features 512 SPUs, 64 TAUs, and 48 Raster Operation Units.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce GTX 580 3GB should in theory perform much faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GTX 580 3GB is a lot (about 72%) more effective at AF than the GeForce GT 640 DDR3. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the GeForce GTX 580 3GB is a better choice, and very much so. (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 maximum amount of data (counted in MB per second) that can be moved past the external memory interface in a second. The number is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better 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 amount of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the graphics card will be at handling 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 video card can possibly write 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 speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.