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Crossfire limitations?

Discussion in 'Graphics Cards' started by Bergkamp, 21 Apr 2010.

  1. Bergkamp

    Gangster

    Joined: 16 Jul 2009

    Posts: 480

    Hi guys. Currently I have an Asus 5850 and I'm just wondering if I was to ever add a second, what sort of limitations could I expect as my motherboard only supports x8 x8 for crossfire.

    Thanks
     
  2. Rroff

    Man of Honour

    Joined: 13 Oct 2006

    Posts: 75,411

    If its PCI-e 2.0 x8 then you shouldn't see any performance degredation, if its PCI-e 1.x then you'll get slightly longer loading times in games and maybe 15% performance drop.
     
  3. jorzeh

    Wise Guy

    Joined: 20 Jun 2009

    Posts: 1,432

    Location: Stockport

    none on a 5850 that boards PCIE 2.0 only problem is when you add a 3rd card and the lanes divide again but 5850 x2 on p55 is fine.
     
  4. Bergkamp

    Gangster

    Joined: 16 Jul 2009

    Posts: 480

    Sweet! Many thanks.
     
  5. Thekwango

    Capodecina

    Joined: 5 Feb 2009

    Posts: 12,503

    Location: Northern Ireland

  6. Bergkamp

    Gangster

    Joined: 16 Jul 2009

    Posts: 480

    Seems you're right Thek, but I could have sworn I read x8 x8 in the documentation. Supplying generic information? I'll have to go dig that out tomorrow actually.
     
  7. jorzeh

    Wise Guy

    Joined: 20 Jun 2009

    Posts: 1,432

    Location: Stockport

    Hmm if it is x4 /x4 then you might run into problems i'm pretty sure it's 8x8x but i would check the manuel for the mainboard first.
     
  8. Thekwango

    Capodecina

    Joined: 5 Feb 2009

    Posts: 12,503

    Location: Northern Ireland

    could be the manual is generic and covers a wide range of boards,

    as per the asus website, hopefuly someone can explain better for you or shed more light

    hope it all works out for ya
     
  9. jorzeh

    Wise Guy

    Joined: 20 Jun 2009

    Posts: 1,432

    Location: Stockport

    How p55 boards normally work is you have a single card it'll run @ 16X if you run 2 cards they divied the 16 lanes into 2 so thats x8 then if you had a 3rd card they half into 4 lanes 4x4x4x4.

    X58 chipset does not 1 lanes 16x and 2 lanes with 2 cards still stay at 16x...

    There are differant revisions of P55 tho so you're mobo might be a lower end p55 chipset it will not.
    for example if you have the Asus P7P55D-E you can run two cards at 8x 8x - thumbs up,
    If you have Asus P7P55D-E LX you can only run 1 card @ 16x (single) or if you use 2 cards you will get the second card running @ 1x which then limits your 16 lanes on both cards to 1 lane there for you can't crossfire - 1x1x.

    I hope i explained this correctly i did take the infomation off Ocuk website so please check the manuel as there should be some sort of divider infomation in there and give us the full extension number of the mainboard and i will check it for you.
     
  10. Gripen90

    Wise Guy

    Joined: 20 Nov 2009

    Posts: 2,020

    Location: Haarby, DENMARK

    I had a Asus P55D Deluxe setup before with the HD5970+HD5850 and the "performance penalty" was nothing to write about - between 0-1%.
     
  11. Thekwango

    Capodecina

    Joined: 5 Feb 2009

    Posts: 12,503

    Location: Northern Ireland

    thats possibly because,

    as per the asus website

    a p7p55d, not the deluxe version has