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Going CrossFire

Discussion in 'AMD / ATI' started by TheMailMan78, Feb 9, 2009.

  1. TheMailMan78

    TheMailMan78 Big Member

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    I have an itch to go crossfire but I'm not sure what it entails. If you see my specs I currently have an HD4850 and a 790GX board. But I have a few questions. FYI I already googled these questions but I want feedback from the TPU community.

    1. Is it better to match brands? I currently have a Visiontek so should I get another one? I ask because I can get some good deals on a HIS card.

    2. Is it difficult to get games to run in crossfire? I'v read you sometimes have to sacrifice a virgin under the full moon.

    3. When running crossfire on my board it cuts the speed from 16x down to 8x. Does crossfire make that much of a difference to justify this?

    4. This question is a n00b one but with my board will I still have to use the little crossfire ribbon?
  2. freaksavior

    freaksavior To infinity ... and beyond!

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    1) No, you do not have to use the same brands. I had a Diamond 3870 and a HIS 3870 in crossfire for a while without issues.

    2) Most games take advantage of crossfire but dont use it correctly i believe. not 100% sure on this one. I know i did get about a 30% increase in fps on the 3870 crossfire setup.

    3) I remember seeing someone do benches on pci-e @ 1,4,8,16 x.16 and 8 wasn't much difference but 4 and 8 was. So you shouldn't see much difference if they were both 16x or if its 8x8

    4) yes, you still need to use the ribbon.
    TheMailMan78 says thanks.
    Crunching for Team TPU
  3. TheMailMan78

    TheMailMan78 Big Member

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    Do they need to be clocked the same? Like if I buy an OC version do you think it will conflict?
  4. freaksavior

    freaksavior To infinity ... and beyond!

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    nope, CCC downclocks the faster card to the slower one. i bios modded both of mine to 850core though, sadly i don't remember the memory speed.
    Last edited: Feb 9, 2009
    Crunching for Team TPU
  5. HossHuge

    HossHuge

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    I just crossfired a Powercolor 4830 with a Gigabyte 4850 without issue. I just had to reload CCC. freaksavior is right about the 30% increase but it does depend on the game. Many people say they have had issues with crossfire but it's been quite smooth for me.

    good luck.
  6. freaksavior

    freaksavior To infinity ... and beyond!

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    i did see certain games get a massive increase in fps. TF2 for example with one 3870 i got about 45fps maxed and with 2 i got about 75fps :)
    Crunching for Team TPU
  7. HossHuge

    HossHuge

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    I know Call of Duty, World at War has a dual GPU option in the menu but I haven't tried it yet.
  8. newtekie1

    newtekie1 Semi-Retired Folder

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    1.) Brand doesn't matter. You can crossfire any 4800 card with any other 4800 card, you can even mix and match models as long as they are both HD4800 cards.

    2.) Well, sometimes it can be a pain, especially with new games. You usually have to wait for ATi to release a new set of drivers, or a hot-fix, with a crossfire profile. Usually, you can rename the new game's exe to an older game that uses the same engine and it will at least get crossfire working with the game, even if it isn't totally optimized. IE: You rename Fallout 3's exe to Oblivion's exe, a lot of people were doing this when Fallout 3 first came out.

    3.) The reduction from x16 to x8 when running crossfire will hurt your crossfire performance, but the extra performance that you get from the second will be huge. You might get a 60% performance boost overall with an x16/x16 setup, but only a 50% increase overall with an x8/x8 setup, but that is still a 50% increase. Either way, the performance difference won't be noticeable in gaming.

    4.)Yes, you need the crossfire ribbon connector.
    Crunching for Team TPU More than 25k PPD
  9. TheMailMan78

    TheMailMan78 Big Member

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    What if I do go with a lower card like the 4830. Will my HD 4850 be clocked down to a 4830 thus robbing it of its crossfire edge?
  10. DRDNA

    DRDNA

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    MailMan dont go lower than your card ...I would recomend another 4850 or a 4850X2.I never Had an issue with CF ...always worked for me ...some games like better than others.
  11. TRIPTEX_CAN

    TRIPTEX_CAN

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    All your questions have been answered but I though I would throw out some things I've experienced.

    1) Sometimes you need to just rename and application to make crossfire work. it's not an exact science but naming Game A to the same name as Game B (when B is known to scale with crossfire) will usually work.

    2) Crossfire + HDMI + multiple monitors and switching primary to secondary.... = EPIC FAIL for me. Hot swapping works fine for single display. Using a DVI screen and a VGA monitor works fine and I assume 2 x DVI monitors works also.

    Single monitors give no problems.
  12. js01 New Member

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    The cards don't clock down I tested this by running my 4830 at 600mhz and 950 mem and my 4850 at 700 1100, I left rivatuner going while playing crysis and both of the cards ran at the speeds they were clocked at.
  13. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    I have a couple questions to add to Mailman's question also:

    1) What is the maximum resolution for a single crossfire bridge?

    Oh and Mailman, any brand is fine and 8x+8x 2.0 isnt limiting at all.
  14. Thrackan

    Thrackan

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    That's good news, I was almost put off from getting xFire later on by that post :D
  15. TRIPTEX_CAN

    TRIPTEX_CAN

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    I believe anything under 1900x1200 should be OK for a single bridge. If I am correct then the bandwidth offered by the second bridge wont even be used unless you game above 2500x1600 with high levels of AA and AF. With that being said I would like to note that I use both bridges and I only game @ 1680x1050.

    The bandwidth theory also plays true with the PCI-E speed. TweakTown did a review placing a P45 vs X48 to crossfire 2 4850s. As biased for the x48 as the review was it still showed that below 1900x1200 having 8x8 vs 16x16 PCI-E makes little to no difference, real world or synthetic.
  16. DRDNA

    DRDNA

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    I thought the second bridge was an option to go to CrossfireX:confused:
  17. 3870x2

    3870x2

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    I have a 4850 im not using, willing to sell for $100, pm me for details.
  18. DRDNA

    DRDNA

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    picture???please;)
  19. TheMailMan78

    TheMailMan78 Big Member

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    I got dibs! Let me talk to my wife and Ill let ya know. You take pay pal?
  20. TheMailMan78

    TheMailMan78 Big Member

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    BACK OFF (growls)
  21. DRDNA

    DRDNA

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    you the man for this card !!!! happy days are coming your way:D
    TheMailMan78 says thanks.
  22. TRIPTEX_CAN

    TRIPTEX_CAN

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    See that's the thing. The second tab on the card is to allow more than 2 cards to be connected, this is the official design which cannont be disputed.

    Some people believe that the second tab also allows for more bandwidth between the cards and thus higher performance. This is all still debatable and I have yet to see any of conclusive data. IF there is an increase in bandwidth I believe the gains will only be noticed at higher resolutions.
  23. TheMailMan78

    TheMailMan78 Big Member

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    No worries man. I have to get clearance first anyway. If she says no its all yours. :toast:

    Edit: I aint going to buy it. So anyone interested please contact 3870x2.
    Last edited: Feb 9, 2009
  24. 3870x2

    3870x2

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    guess i should say it is under water, and my dog ate the stock fan.... ill have it in my FS thread in a while.
  25. DRDNA

    DRDNA

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    aww to bad man...a 4850 for a 4830 price.

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