Compare any two graphics cards:
GeForce 9800 GT 1GB vs GeForce GT 640 DDR3
IntroThe GeForce 9800 GT 1GB has a GPU core clock speed of 600 MHz, and the 1024 MB of GDDR3 memory runs at 900 MHz through a 256-bit bus. It also is made up of 112 Stream Processors, 56 Texture Address Units, and 16 Raster Operation Units.
Compare all of that to the GeForce GT 640 DDR3, which uses a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 RAM runs at a frequency of 1782 MHz on this particular card. It features 384 SPUs as well as 32 Texture Address Units and 16 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce 9800 GT 1GB, in theory, should be a bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce 9800 GT 1GB is a small bit (more or less 17%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GT 640 DDR3 is much (about 50%) faster with regards to anti-aliasing than the GeForce 9800 GT 1GB, and 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 largest amount of information (measured in MB per second) that can be moved over the external memory interface in a second. The number is calculated by multiplying the interface width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics 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 number of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel 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 reach the max fill rate.