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Radeon 7970: dual 16x vs. dual 8x

As absurd and overkill as it is, I was wondering if there was a large difference in performance if you would run two Radeon 7970s in crossfire in 16x speeds versus 8x.

Thanks! :D
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  1. A difference of ~10% between the 2 configurations I would say. The 7970 will fully saturate the x8/x8 slots in some cases - especially when overclocked.
  2. 7970 is a high end card, therefore it's most likely to have full bandwidth of 16x/16x to work %100 without bottleneck. If you want a board that has x8/x8 (PCI-E 2.0 mostly) I'd recommend you to get x16/x16 instead.
  3. refillable said:
    7970 is a high end card, therefore it's most likely to have full bandwidth of 16x/16x to work %100 without bottleneck. If you want a board that has x8/x8 (PCI-E 2.0 mostly) I'd recommend you to get x16/x16 instead.


    Yeah but if as deadjon said the difference is only a minimal 10% I'd stick with the 8x speeds. For now anyway I'm going to use a single card which will run at 16x and that should be more than enough for the time being. If I want a dual 16x I would also need to get a x79 board which runs on the overpriced i7-3960 since the intel socket 1155 boards I'm looking at don't apparently support dual 16x speeds.

    Btw the slots will be 3.0 dunno if that makes a large difference to a 8x speed 2.0 slot...
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  5. FunSurfer said:


    This is PCI-E 2.0, Ivy bridge has not been released yet.

    I would suggest looking at the GTX580 test for x8/x8 and figuring it out from there.

    The 7970 is 10 to 20% faster than the GTX580 3GB @ Stock speeds I believe.
  6. deadjon said:
    This is PCI-E 2.0, Ivy bridge has not been released yet.

    I would suggest looking at the GTX580 test for x8/x8 and figuring it out from there.

    The 7970 is 10 to 20% faster than the GTX580 3GB @ Stock speeds I believe.


    I don't understand "This is PCI-E 2.0", the bandwidth is 16GB/sec, how can PCI-E 2.0 support that?
  7. sosofm said:


    Yeah looked at the link from FunSurfer, the difference between a pcie 3.0 x16 vs. x8 is nothing much.
  8. Best answer selected by tha1.
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