Compare any two graphics cards:
Radeon HD 4890 2GB vs Radeon HD 5970
IntroThe Radeon HD 4890 2GB comes with a core clock speed of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also uses a 256-bit bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.
Compare that to the Radeon HD 5970, which features a clock speed of 725 MHz and a GDDR5 memory speed of 1000 MHz. It also features a 256-bit bus, and makes use of a 40 nm design. It is made up of 1600 SPUs, 160 TAUs, and 64 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 5970 should perform much faster than the Radeon HD 4890 2GB in general. (explain)
Texel RateThe Radeon HD 5970 is much (approximately 480%) faster with regards to AF than the Radeon HD 4890 2GB. (explain)
Pixel RateIf using a high screen resolution is important to you, then the Radeon HD 5970 is superior to the Radeon HD 4890 2GB, 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.
One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.
Memory Bandwidth: Memory bandwidth is the maximum amount of data (measured in MB per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at 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 card can possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka 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, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.