Compare any two graphics cards:
GeForce GT 640 DDR3 vs Radeon HD 4850 2GB
IntroThe GeForce GT 640 DDR3 comes with clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 32 Texture Address Units and 16 ROPs.
Compare those specs to the Radeon HD 4850 2GB, which comes with a core clock speed of 625 MHz and a GDDR4 memory frequency of 993 MHz. It also makes use of a 256-bit bus, and uses a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the Radeon HD 4850 2GB is 11% faster than the GeForce GT 640 DDR3 overall, because of its higher bandwidth. (explain)
Texel RateThe GeForce GT 640 DDR3 will be a little bit (more or less 15%) more effective at AF than the Radeon HD 4850 2GB. (explain)
Pixel RateThe GeForce GT 640 DDR3 is much (approximately 44%) more effective at FSAA than the Radeon HD 4850 2GB, and will be able to handle higher resolutions more effectively. (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 (counted in MB per second) that can be moved across the external memory interface within a second. The number is calculated by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 processed per second. This figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.
Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.