Compare any two graphics cards:
Radeon HD 4870 X2 vs Radeon HD 5870
IntroThe Radeon HD 4870 X2 features a clock frequency of 750 MHz and a GDDR5 memory speed of 900 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.
Compare all of that to the Radeon HD 5870, which features a clock frequency of 850 MHz and a GDDR5 memory speed of 1200 MHz. It also features a 256-bit bus, and makes use of a 40 nm design. It is comprised of 1600(320x5) SPUs, 80 Texture Address Units, and 32 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 4870 X2 should be 50% quicker than the Radeon HD 5870 overall, due to its higher data rate. (explain)
Texel RateThe Radeon HD 5870 should be just a bit (approximately 13%) faster with regards to anisotropic filtering than the Radeon HD 4870 X2. (explain)
Pixel RateThe Radeon HD 5870 should be a bit (more or less 13%) better at FSAA than the Radeon HD 4870 X2, and also able to handle higher screen resolutions while still performing well. (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.
Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.
Memory Bandwidth: Bandwidth is the largest amount of information (counted in MB per second) that can be transported past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the 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 number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total number of texture units by the core speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of 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 fill 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 potential to get to the maximum fill rate.