Pcie 8x vs 16x

Hi all,
Im looking at upgrading my motherboard soon and looking at going to sli/crossfire, does anyone know what the proformance difference is between them. Most boards run a single gpu at 16x but in crossfire/sli some run them both in 8x or 16x and 4x, i have seen some boards that run cf/sli both in 16x but costs a extra £50-£60.

Is this worth the money and whats the difference in the proformance on the three types of pcie.

Any information will be great, thanks.
9 answers Last reply
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  1. Google will drown you with answers mate.

    Pci-E 2.0 is 2x faster than the equivilent PCi-e 1.0.

    thus PCI-e 1.0 @ 16x is equal to PCI-e 2.0 @ 8x.

    typically, PCI-e 2.0 @ 8x is all you need for most high end cards. especially if you are running a multi card system.
  2. customisbetter,
    thanks for your help mate, i am running pci-e 1.0 at 8x and looking at running a single hd5770 on my new motherboard that will be at pci-e 2.0 16x, but when i will be putting 2x hd5770 they will both be running at 8x on the crossfire so will there be much of a performance difference if it is going from 16x on a single to 8x on crossfire.

    thanks for your help
  3. Just finished reading mazier faqs sticky and gave a lot of details, still didnt say what customisbetter said and thats what i needed to know so thanks again all.
  4. No probs. two 5770s is a great setup. enjoy!
  5. x8 crossfire should be fine, just avoid x4.
  6. My recollection is that bandwidth doesn't start to get squeezed at 8x until you hit the point of twin GTX 260s or twin 5770's
  7. JackNaylorPE,
    I was looking at getting the Asus Crosshair III as it had both pci-e at 16x in crossfire but i have been looking at the Asus M4a79XTD-evo for half the price but it only has 8x in Crossfire. I am putting the 5770s in to crossfire and want to get the most i can out of them without them getting bottlenecked.
  8. @ Boden08: Have a read here to set your mind at rest, but you'll see no performance loss at PCI-E 2.0 X8 using dual HD5770 cards:


    When reading, remember they are using more powerful cards!
  9. Coozie7,
    Thanks for the link that was a intresting read and there realy is not much difference between them and some times 8x is above 16x so it just depends on the games that are being played but this does put my mind at rest when i will be saving 54pound for 8x when there is not much performance difference between the two.

    thank you very much.
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