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  1. #1
    Joined
    Dec 2003
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    Virginia
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    52
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    279

    Crossfire question

    I recently moved from Virginia to Arkansas and unfortunately my rig did not make the trip successfully. When I got to AR I noticed the CPU cooler was loose and realized a tab on the hold down was broken. I replaced it, put the cooler back on but cannot get the system to boot. Not sure what happened but I am assuming the MOBO is dead from the trip. Anyway I just decided it was time for a new system rather than figure out all the possibly problems (I had been running an MSI K9A2 with an AMD 940 black)

    The new rig will be an ASUS M5a99FX with a Phenom 6300-Vishera.

    My question.....the old system had a relatively new (1 year old) Radeon 6850 in it. I bought a Radeon 7870 for the new one. What is my best performance going to be, the 7870 by itself, or can I run those two cards in crossfire mode? I have never done crossfire and to be honest not all the familiar so I don't know if you need two of the exact same card.

    Also, would I be better off returning the 7870 and getting another 6850? The price difference was 30 bucks, the 7870 is a Sapphire, the 6850 for sale is a VisionTek. The 6850 I have in the rig now is an MSI.

    Anyway, thanks for the help in understanding exactly how all this works...I simply don't understand Crossfire enough to understand what will give me the best performance. When I bought the 7870 I thought the 6850 was older than it was. I looked up the order history and realized that it was not that old so I am wondering if I can use it.

    TIA
    Why we are Folding - Movie



    AMD Phenom 6300 Vishera Black edition, ASUS M5A99FX Pro 2.0
    16GB GSkill Ripjaw DDR3 1600, MSI HD7870
    Enermax ETS-T40 Cooler
    Rosewill Xtreme RX-850 Asus Sata DVD burner
    WD Caviar 500GB Sata,WD Caviar 320GB SATA.

  2. #2
    Joined
    Sep 2002
    Posts
    5,358

    Re: Crossfire question

    The 7870 is quite a bit faster than the 6850 and most definitely worth the $30 difference. The simple answer is: Get rid of the 6850 and just stick with the single 7870. If you in theory (shouldn't actually be possible http://sites.amd.com/PublishingImage...hart_1618W.jpg, since not the same gen chips) got CF to work the 6850 would basically be dragging the performance down as e.g. you'd lose the advantage of the doubled memory size on the 7870.

  3. #3
    Joined
    Nov 2005
    Posts
    507

    Re: Crossfire question

    If you really want to do Crossfire, I would get another 7870. Otherwise, get rid of the 6850 and stick with a single 7870. I'm running two 7850's right now, and I have one turd of a game that never did get along very well with Crossfire or with SLI and it happens to be Diablo 3, cause of the way that game was programmed by Blizzard. Only way Diablo 3 runs great, and it ticks me off is if I run it off a USB 3 memory stick or off an SSD which one shouldn't have to, to do, the game should run great off a standard SATA 6G(3) harddrive, but it doesn't.

  4. #4
    Joined
    Mar 2003
    Location
    Central NJ
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    11,090

    Re: Crossfire question

    I think the cards need to be based on the same GPU chip in the same generation to work together.. i.e. 7970+7950 is possible (both 79X0 cards), but 7970+7870 is not, neither is 7870+6850. I think the 7870 is fast enough that 2x 6850's wouldn't give you a big enough performance improvement to warrant the extra power/heat/complexity.


    Trust me, I do science
    My Hardware, Past and Present

  5. #5
    Joined
    Feb 2004
    Location
    Janesville, Wi
    Posts
    6,450

    Re: Crossfire question

    Quote Originally Posted by Activate: AMD View Post
    I think the cards need to be based on the same GPU chip in the same generation to work together.. i.e. 7970+7950 is possible (both 79X0 cards), but 7970+7870 is not, neither is 7870+6850. I think the 7870 is fast enough that 2x 6850's wouldn't give you a big enough performance improvement to warrant the extra power/heat/complexity.
    It should also be mentioned that the 7970 can be xfired with the R9-280x (rebrand)


  6. #6
    Joined
    Dec 2003
    Location
    Virginia
    Age
    52
    Posts
    279

    Re: Crossfire question

    Thanks for the replies....explains a lot and I appreciate the help.
    Why we are Folding - Movie



    AMD Phenom 6300 Vishera Black edition, ASUS M5A99FX Pro 2.0
    16GB GSkill Ripjaw DDR3 1600, MSI HD7870
    Enermax ETS-T40 Cooler
    Rosewill Xtreme RX-850 Asus Sata DVD burner
    WD Caviar 500GB Sata,WD Caviar 320GB SATA.

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