Compare any two graphics cards:
GeForce GTX 470 vs Radeon HD 4850 1GB
IntroThe GeForce GTX 470 comes with a clock frequency of 607 MHz and a GDDR5 memory speed of 837 MHz. It also uses a 320-bit memory bus, and makes use of a 40 nm design. It is made up of 448 SPUs, 56 Texture Address Units, and 40 ROPs.
Compare that to the Radeon HD 4850 1GB, which comes with clock speeds of 625 MHz on the GPU, and 993 MHz on the 1024 MB of GDDR4 memory. It features 800(160x5) SPUs as well as 40 TAUs and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the GeForce GTX 470 should in theory be a lot superior to the Radeon HD 4850 1GB overall. (explain)
Texel RateThe GeForce GTX 470 should be a lot (more or less 36%) better at anisotropic filtering than the Radeon HD 4850 1GB. (explain)
Pixel RateThe GeForce GTX 470 will be a lot (more or less 143%) more effective at anti-aliasing than the Radeon HD 4850 1GB, and also will be capable of handling higher 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.
Memory Bandwidth: Memory bandwidth is the max amount of information (counted in megabytes per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the bus width by its memory clock speed. If the card has DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range 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 worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.
Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel 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 max fill rate.