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HD 5850 Specification
ATI’s HD 5850 card is based upon the Cypress Pro chip. This chip has 2.15 Billion transistors and is manufactured on TSMC’s 40nm fabrication process. The chip is around 334mm2 which is quite small for such a large number of transistors. ATI says that their HD 5850 has up to 2.09 Teraflops of computing power single precision. Two of the HD 5850s in CrossfireX mode output up to 4.18 TeraFlops.  Drivers  Drivers  Drivers  Drivers The HD 5850 is clocked at 725MHz for the core and 4GHz effective for the memory. The key feature here is that the memory is clocked at 1GHz, but doubled for double data rate and doubled again for GDDR5 memory. This provides each card 128GB of memory bandwidth. The Texel fillrate is 52.2 Gigatexels and the pixel fill rate is 23.2 Gigapixels a second. ATI introduced Crossfire in 2005 with the release of the X800 cards. The first generation of Crossfire required a Master and a Slave video card, an external Crossfire cable and a Crossfire compliant motherboard with two PCIe slots as the cards needed a composite chip to run in Crossfire mode. The X850XT Master card used a Silicon Image compositing chip (Sil 163 TMDS) and the maximum resolution of Crossfire first generation was 1600x1200 at 60Hz or 1920x1440 at 52Hz meaning that most people needing high resolution gaming at high refresh rates chose another solution. ATI removed the limitation with the X1800 series as it required no Master card and there wasn’t a compositing chip. With the advent of the X1800 series the Crossfire dongle was no longer required. What you needed to achieve this was a CrossFire Xpress 3200 motherboard and two ATI RADEON cards that communicated over the PCI Express bus removing the compositing chip from the card. Today’s implementation of Crossfire on all ATI HD 2xxx series and above has implemented a bridge system much like NVIDIA’s SLI implementation. Two cards or more (Up to four), assuming the motherboard supports four video cards, and Crossfire, can be daisy-chained to each other improving performance over a single video card. ATI uses three methods to render with CrossfireX: Scissors, Checker board mode and Alternate Frame Rendering Mode. Scissors mode splits the frame into half with one video card rendering the top half of the image and the other rendering the bottom half of the image with three cards splitting the screen into three and four into quarters. Checker board has the image split into smaller squares which are assigned to different cards. Alternate Frame Rendering has the first video card render one whole frame, the second the next frame, etc. In most cases Scissors mode is the most inefficient as some parts of a rendered scene are more complex than others, meaning that one card may render part of a scene faster than another with the card waiting on the second card to render its part of the scene. AFR is most useful because the image usually doesn’t change much from one frame to the next, meaning the workload is mostly similar so having one card render an image then the next card render a slightly different image is more efficient than having one card render part of a scene as parts of the scene can have much more geometry or pixels than others. Contents:
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