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Crossfire Eyefinity PCIe 16x / 4x VS 8x / 8x

Discussion in 'Videocards - AMD Radeon' started by lenne, Nov 11, 2012.

  1. lenne

    lenne Master Guru

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    GPU:
    1080 GTX Gainward
    I thought im gonna share my recent experience with my crossfire setup with you guys because theres a lot of misinformation in the wild how just 4 Pcie lanes for the second card affect Crossfire with Eyefinity resolutions.

    Coming from an 4870x2 i swore to myself to never use crossfire again, but 6950s being really cheap now and a single 6950 not really enough to drive Battlefield 3 across all monitors ( I used BF3 Borderless windowed to reduce the horizontal resolution which worked just fine ) I just bought another card.

    After installing everything i immediatly noticed that there was a performance gain but nowhere near to what i expected, BF3 running around 40fps 64Player MP with huge microstuttering slowdowns into the 30s ( All settings to low 6000x1080 )

    Crysis 2 unplayable, even though the framerate was acceptable there was so much rubberbanding making it impossible to aim.

    What now ? knowing that crossfire drivers for these two games matured a lot and scaling should be alot better i tried to find the culprit, new PSU made no difference ( even though it allowed me to oc the cards a bit further )

    I noticed only the that my old board was running the PCIe slots in crossfire @16x 2.0 and the second slot at only 4x 2.0

    By then i already had the feeling that there must be an "deeper" problem then just drivers, the bf3 slowdowns couldnt be explained blaming it just on the drivers, they just felt "not right" and everytime they occured my system started to microstutter a lot, giving me the impression that one card was just unalbe to deliver the frames in time.

    So i switched to an Z77 board which delivers 8x 2.0 lanes to both cards.

    Man what a massive difference that made, BF3 runs now silky smooth @ 6000x1080 64P MP with medium settings, Crysis 2 rubberbanding is completely gone.

    Another thing which was quite amazing is how microstuttering with crossfire is largely gone, the 4870x2 was just a mess compared to the two 6950s.

    I never thought i would say that after the experience i made with the 4870x2 but im really happy now with how crossfire performs.

    Conclusion: dont listen to ********* found everywhere telling that just 4x 2.0 lanes impact performance by only 5%, for eyefinity and crossfire it makes pretty much every title unplayable.


    Please share your thoughts / experiences on this topic, if you google it theres nothing really to be found, for me buying a new mb was just a shot in the dark, even though it worked out quiet well.
     
  2. ArgonV

    ArgonV Master Guru

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    GPU:
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    I agree, that's why I bought the X58 platform when I did. A full 16x to both PCIe slots. Makes crossfiring my two 5870's a very fast option on monitors below 22". However, I find I'm hitting a bottleneck now going from my old triple screen setup to my new 24" triple screen setup. The two 5870's just don't have the power anymore like when I was only running three 19" screens.
     
  3. lenne

    lenne Master Guru

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    I dont know how 8x 2.0 / 8x 2.0 compares to 16x 2.0 / 16x 2.0 because these boards are much more expensive but i think that would really be a minor improvement, maybe the next generation of cards will utilise that much bandwidth, but the z77 chipset is able together with an ivy bridge chip to deliver 8x 3.0 / 8x 3.0 which should be enough again even for the next generation of cards ( another point which made it easier to buy a new board ;) )
     
  4. MeMeMe

    MeMeMe New Member

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    GPU:
    CF HIS 7970 IceQ x2 Turbo
    I haven't played BF3. Is this a full screen mode? Crossfire only works in full screen mode, not windowed mode.
     

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