Compare any two graphics cards:
GeForce GT 340 1GB vs Radeon HD 4870 512MB
IntroThe GeForce GT 340 1GB has a GPU clock speed of 550 MHz, and the 1024 MB of GDDR5 RAM is set to run at 850 MHz through a 128-bit bus. It also is comprised of 96 Stream Processors, 32 TAUs, and 8 Raster Operation Units.
Compare all that to the Radeon HD 4870 512MB, which makes use of a 55 nm design. AMD has set the core speed at 750 MHz. The GDDR5 RAM runs at a frequency of 900 MHz on this particular card. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 4870 512MB should perform quite a bit faster than the GeForce GT 340 1GB overall. (explain)
Texel RateThe Radeon HD 4870 512MB should be a lot (about 70%) better at AF than the GeForce GT 340 1GB. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the Radeon HD 4870 512MB is a better choice, and very much so. (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 largest amount of information (counted in megabytes per second) that can be moved over the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total number of texture units by the core speed of the chip. The better this number, the better the video 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 maximum number of pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. The number 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 output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.