Compare any two graphics cards:
GeForce GT 640 DDR3 vs Radeon HD 4850 2GB
IntroThe GeForce GT 640 DDR3 has a clock speed of 900 MHz and a DDR3 memory speed of 1782 MHz. It also uses a 128-bit bus, and makes use of a 28 nm design. It is comprised of 384 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.
Compare all of that to the Radeon HD 4850 2GB, which comes with a core clock speed of 625 MHz and a GDDR4 memory speed of 993 MHz. It also makes use of a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 4850 2GB should theoretically be a small bit faster than the GeForce GT 640 DDR3 overall. (explain)
Texel RateThe GeForce GT 640 DDR3 will be a small bit (about 15%) more effective at anisotropic filtering than the Radeon HD 4850 2GB. (explain)
Pixel RateThe GeForce GT 640 DDR3 will be quite a bit (about 44%) better at AA than the Radeon HD 4850 2GB, and also should be 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: Bandwidth is the max amount of data (counted in MB per second) that can be transferred across the external memory interface in a second. The number is calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the 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 amount of texture map elements (texels) that can be applied per second. This is worked out by multiplying the total amount of texture units by the core clock 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 applied per second.
Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to its local memory per 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 - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.