How do i get crossfire to work on my pc

ok so i just got a 3870 and a 3870x2 and want to run them in crossfire or trifire as its known to others. however i connect both cards and connect the bridge and my cards dont seem to have any performance increase. i play wow alot and find that now my graphics seem worse the world from a distance is shadowed and stutters. now i ran bench marks on my cards and wanted to see so my 3870x2 scored 84 k points on 3dmark03 and my crossfire set scored 38k points wtf is wrong.

facts i am only running a single monitor
have amd phenom 4
12gb corsair ram
crossfire ready board
in catalyst crossfire is enabled
both cards work 100%
850w psu so power isnt issue

i have read that the 3870 and 3870x2 can be paired in crossfire however i think im missing something about it as i cant seem to get the pair to work my 3870x2 takes all gpu load. i think it may be a driver issue but im running windows 7 64bit and have latest catalyst drivers.


please any info would be amazing and or advice
8 answers Last reply
More about crossfire work
  1. Yes, they should be able to be connected together, provided the chipset will work with them. See if you have a BIOS update. I don't think you will have any performance increase in WOW with using dual cards though.
  2. Do you have the new card in the correct slot?
    Set to slots to proper mode? (some boards have option of running a single card at x16 but the other x16 slot gets disabled. Enabling the second x16 slot sets both in x8/x8 mode)
  3. how would i go about setting them up if they arent i think they should be. and i know i had a single 8800gtx running wow on ultra not sure why 2 in xfire are playing up. ive never had those shadeing issues before until i tried getting my crossfire working. any more advice if bios update doesnt work and enabling pci slots.
  4. To be completely frank, I think it's time for an upgrade. I know not exactly what you wanted but a single 7850 is just as powerful if not more powerful than your three 3870's (when their CF is running perfectly that is). Also you don't have nearly as many problems and it's going to work with every game without all the fuss.
  5. popatim said:
    Do you have the new card in the correct slot?
    Set to slots to proper mode? (some boards have option of running a single card at x16 but the other x16 slot gets disabled. Enabling the second x16 slot sets both in x8/x8 mode)


    hey i now see that my main gpu is running as 16x and other at 8x any idea how id go about changing the settings for this?
    my mobo is a Asus M4A79XTD if that helps.

    let me know asap thanks pop
  6. First I would move the x2 to the x16 slot. Asus site doesnt work right for me so I cant download you're manual to see if there is another setting.
  7. popatim said:
    First I would move the x2 to the x16 slot. Asus site doesnt work right for me so I cant download you're manual to see if there is another setting.



    when i have just the x2 in top slot its automatically x16 but when i add 2nd card it stays x16 and 2nd slot becomes x8.
    when using x2 in bottom slot its same story there must be another way to get both to run at x8
  8. putka123gtr said:
    when i have just the x2 in top slot its automatically x16 but when i add 2nd card it stays x16 and 2nd slot becomes x8.
    when using x2 in bottom slot its same story there must be another way to get both to run at x8


    Edit, I misread your post, though you were trying to run both slots at 16 speeds which your system can't do. It is designed to run at 8 speeds when two cards are in though.
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