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Is my crossfire-configuration bottlenecked?

Discussion in 'AMD / ATI' started by Dawgstah, Jul 6, 2014.

  1. Dawgstah New Member

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    I have two Sapphire Radeon 280X in crossfire on a ASUS P9X79 motherboard. The motherboard has the latest BIOS installed. The thing is that when I look in to the hardware specs in the Catalyst Control Center, I notice something strange. The card listed as the primary adapter shows its PCIe setting as 3.0, while the one listed as linked adapter only shows its setting as PCIe 2.0. What can I do to solve this?
     
  2. Jetster

    Jetster

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    Not sure if you can change the way its displayed but no. No bottleneck there
     
  3. Dawgstah New Member

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    Thanks! Both run at x16. But isn't it a bit strange that the one runs at 3.0 while the other one at 2.0?
     
  4. RealNeil

    RealNeil

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    That refers to the capability of the slots that the cards are installed into. The top one is PCI-E 3.0 X16 capable, and the fourth is PCI-E 2.0 X16 Capable.

    That board runs the two cards at true X16 speeds, so there is nothing to fix. Even if you were running at X8 by X8 speeds, those cards couldn't saturate your available bandwidth.
    I'll bet that it's a great gaming rig,.........:peace:
     
  5. eidairaman1

    eidairaman1

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    The rig is fine
     
  6. Aquinus

    Aquinus Resident Wat-man

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    I don't think it's possible to bottleneck the 280Xs on a P9X79 unless you were using a really low clocked skt2011 Xeon. Are you talking about the LE or Deluxe/Pro?

    It would be helpful if you filled in your specs, but I suspect the bottleneck you're looking for doesn't exist.
     
  7. RealNeil

    RealNeil

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    The difference between PCI-E 3.0 and 2.0 is,.....PCI-E 3.0 has twice the bandwidth per lane that 2.0 does. Two cards in crossfire will run at PCI-E 2.0 speeds maximum, because of the one slot only being able to run at that speed.
    Present day GPUs were never able to completely saturate a X8 or X16 2.0 PCI-E bus, let alone 3.0.

    So, you're getting the full speed performance of those two GPUs with that board.
     

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