Compare any two graphics cards:
GeForce GT 640 DDR3 vs Radeon HD 5850
IntroThe GeForce GT 640 DDR3 comes with a GPU clock speed of 900 MHz, and the 2048 MB of DDR3 memory runs at 1782 MHz through a 128-bit bus. It also is made up of 384 Stream Processors, 32 TAUs, and 16 Raster Operation Units.
Compare those specs to the Radeon HD 5850, which features a clock speed of 725 MHz and a GDDR5 memory speed of 1000 MHz. It also uses a 256-bit bus, and makes use of a 40 nm design. It features 1440(288x5) SPUs, 72 TAUs, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the Radeon HD 5850 should in theory be quite a bit better than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe Radeon HD 5850 should be a lot (more or less 81%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)
Pixel RateIf running with a high resolution is important to you, then the Radeon HD 5850 is the winner, by a large margin. (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 information (measured in MB per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.