Compare any two graphics cards:
Radeon HD 5870 vs Radeon HD 6870
IntroThe Radeon HD 5870 features a GPU core clock speed of 850 MHz, and the 1024 MB of GDDR5 memory runs at 1200 MHz through a 256-bit bus. It also is comprised of 1600(320x5) SPUs, 80 Texture Address Units, and 32 Raster Operation Units.
Compare all that to the Radeon HD 6870, which has a core clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also features a 256-bit bus, and uses a 40 nm design. It features 1120 SPUs, 56 Texture Address Units, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the Radeon HD 5870 will be 14% quicker than the Radeon HD 6870 in general, due to its greater bandwidth. (explain)
Texel RateThe Radeon HD 5870 should be a lot (approximately 35%) more effective at texture filtering than the Radeon HD 6870. (explain)
Pixel RateThe Radeon HD 6870 is just a bit (about 6%) more effective at FSAA than the Radeon HD 5870, and will be capable of handling higher resolutions without slowing down too much. (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.
Radeon HD 5870
Radeon HD 6870
Memory Bandwidth: Memory bandwidth is the maximum amount of data (measured in MB per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This is worked out 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.
Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes 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 ability to get to the max fill rate.
Radeon HD 5870
Radeon HD 6870