Compare any two graphics cards:
GeForce GTX 460 (OEM) vs Radeon HD 4870 2GB
IntroThe GeForce GTX 460 (OEM) features a core clock speed of 650 MHz and a GDDR5 memory speed of 850 MHz. It also uses a 256-bit memory bus, and uses a 40 nm design. It is comprised of 336 SPUs, 56 Texture Address Units, and 32 ROPs.
Compare that to the Radeon HD 4870 2GB, which features a GPU core clock speed of 750 MHz, and 2048 MB of GDDR5 RAM set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
Power Usage and Theoretical BenchmarksBoth cards have the same power consumption.
In theory, the Radeon HD 4870 2GB should perform a small bit faster than the GeForce GTX 460 (OEM) overall. (explain)
Texel RateThe GeForce GTX 460 (OEM) will be much (about 21%) better at anisotropic filtering than the Radeon HD 4870 2GB. (explain)
Pixel RateThe GeForce GTX 460 (OEM) will be much (more or less 73%) better at AA than the Radeon HD 4870 2GB, and will be able to handle 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.
Memory Bandwidth: Memory bandwidth is the max amount of information (measured in MB per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory clock speed. If it uses DDR type memory, it should 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 AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is calculated by multiplying the total amount of texture units by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum number of pixels the video 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 amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called 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 reach the maximum fill rate.