Compare any two graphics cards:
GeForce 9800 GT 1GB vs GeForce GT 640 DDR3
IntroThe GeForce 9800 GT 1GB comes with 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 SPUs, 56 TAUs, and 16 ROPs.
Compare those specs to the GeForce GT 640 DDR3, which comes with a core clock frequency of 900 MHz and a DDR3 memory speed of 1782 MHz. It also makes use of a 128-bit memory bus, and makes use of a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce 9800 GT 1GB should theoretically be a little bit faster than the GeForce GT 640 DDR3 in general. (explain)
Texel RateThe GeForce 9800 GT 1GB will be a small bit (about 17%) better at AF than the GeForce GT 640 DDR3. (explain)
Pixel RateThe GeForce GT 640 DDR3 will be quite a bit (about 50%) faster with regards to AA than the GeForce 9800 GT 1GB, and will be able to handle higher screen resolutions while still performing well. (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 information (measured in MB per second) that can be transferred over the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, 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 can be processed in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the card's 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 output rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.