Compare any two graphics cards:
Radeon HD 4870 X2 vs Radeon HD 5870
IntroThe Radeon HD 4870 X2 has a GPU core clock speed of 750 MHz, and the 1024 MB of GDDR5 memory runs at 900 MHz through a 256-bit bus. It also is made up of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
Compare all that to the Radeon HD 5870, which uses a 40 nm design. AMD has set the core speed at 850 MHz. The GDDR5 RAM is set to run at a frequency of 1200 MHz on this card. It features 1600(320x5) SPUs along with 80 TAUs and 32 Rasterization Operator Units.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Theoretically speaking, the Radeon HD 4870 X2 should be quite a bit faster than the Radeon HD 5870 in general. (explain)
Texel RateThe Radeon HD 5870 is a little bit (more or less 13%) more effective at AF than the Radeon HD 4870 X2. (explain)
Pixel RateIf using a high screen resolution is important to you, then the Radeon HD 5870 is superior to the Radeon HD 4870 X2, but only just. (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: Memory bandwidth is the maximum amount of information (in units of MB per second) that can be transported over the external memory interface in a second. It's worked out by multiplying the bus width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, 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 is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.