Radeon HD 3870 x2 in Mac Pro - HELP!

Discussion in 'Mac Pro' started by Sveetly, Aug 27, 2008.

  1. Sveetly macrumors member

    Sveetly

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    #1
    Hello, after spending a zillion dollars getting overnight shipment on a 3870 x2, as well as two of these http://shop.ati.com/product.asp?sku=3280778, I went to set it up, when I realized that I haven't a clue where to plug in the power cords. I have a 2007 mac pro, if that helps.

    Thank in advance!
     
  2. kahine macrumors regular

    Joined:
    Jul 10, 2008
    #2
    On the 2008 version the power connectors are in the top left side of the motherboard right behind the drive/fan cage

    But the 3870's come with their own power cords if they are the Mac version anyway ,
     
  3. Sveetly thread starter macrumors member

    Sveetly

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    #3
    Thanks!

    Thank you!

    It's the same on the 2007 model. Plugged in now. Can't wait to try it out :D
     
  4. mastersoft macrumors member

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    Sep 26, 2007
    #4
    tell us more ? it works ?

    post pictures please
     
  5. Sveetly thread starter macrumors member

    Sveetly

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    #5
    Yes. In fact, it does work. But only under Windows. But you don't have to remove it to use OS X, just leave two cards in.

    ONE FINAL QUESTION: Is there a performance disadvantage using 2 6-pins connectors instead of on 8-pin and one 6-pin?

    Thanks!
     
  6. Rankrotten macrumors 6502

    Rankrotten

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    #6
    No disadvantage you just can't overclock it beyond its defaults
     
  7. Sveetly thread starter macrumors member

    Sveetly

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    #7
    I couldn't control the fan speed either. Is that also a result of the lack of 2 pins?
     
  8. Sveetly thread starter macrumors member

    Sveetly

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    #8
    IMAGES:
    [​IMG]

    [​IMG]
     
  9. mainemacuser macrumors newbie

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    #9

    Aaahhh,

    Geek porn, very nice. :D
     
  10. Sveetly thread starter macrumors member

    Sveetly

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    #10
    Haha. I've never heard that term before!
     
  11. sactownbwoy macrumors regular

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    Aug 28, 2008
    #11
    The fan speed is set by the bios of video card to spin up or down automatically depending on temp of card. There are programs that will allow you to set the fan speeds but they are for windows. I don't know of any for macs (I don't own one).
     
  12. Sveetly thread starter macrumors member

    Sveetly

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    #12
    I'm using RivaTuner under Windows XP Pro.

    It recognizes the card and thinks it's letting me control the speed, but the speed doesn't change.
     
  13. FireSlash macrumors member

    Joined:
    Nov 11, 2007
    #13
    They won't work for mac because the mac does not initialize the card's BIOS; so even if you altered the card's setting to spin at a lower speed, the card's fan control system would never kick in until you booted to windows.
     
  14. mastersoft macrumors member

    Joined:
    Sep 26, 2007
    #14
    WOOW....coool

    let me understand...i see you have only 1 card ...ATI 3870X2... that mean you use only WINDOWS ????

    where did u get the power cable for the ATI 3870X2 ...?? and from where did u get the POWER ????

    QUESTION : if i use ATI 2600XT for OSX and buy another card like 3870x2 for WINDOWS how can i SELECT which one to USE the O.S ???

    can u post picture to see from where is coming the power cable...from the motherboard ..or from PSU ?

    can u
    thx man
     
  15. Sveetly thread starter macrumors member

    Sveetly

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    #15
    Haha. No. I use Mac as well. The other card (7300GT) was out because I'd been reconnecting the power supply earlier in the day. (The cord fell out! You have remove half the stuff in the case to reconnect it :eek:) (I think you could see the "3" on the outside of the case through where the 7300 would usually be.)

    The power cable is found here: http://shop.ati.com/product.asp?sku=3280778 (You need two. You might already have one)
    They plug in the upper left corner of the board. Right at the edge of the front fan casing (grey plastic thing.) See image below (image taken from the Mac Pro Service Manual.)

    [​IMG]

    You can ask around . . . but for me it uses only the card my monitor is plugged into. I've tried plugging two cords into my monitor (one DVI and one VGA) and switching between them, but if both cords are plugged in, it defaults the DVI card :(

    Hope that helps! :)
     
  16. mastersoft macrumors member

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    #16
    WOW....cool man.. thx for the reply

    PS. u have 1 private message
     
  17. Sveetly thread starter macrumors member

    Sveetly

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    #17
    I do believe I've answered it.
     
  18. RoninXI macrumors regular

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    #18
    Is the noise the only problem (aside from it only using 1 GPU) or does it not work in OSX?
     
  19. nanofrog macrumors G4

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    May 6, 2008
    #19
    Sveetly already verified it's windows only. :(
    If you do install one, just be mindful of the PCIe power cables. Use the 6 pin connector on the logic board (cable needed). You can see it in the image posted above. The 8 pin cable, supplied with the card, can be used with the 4 pin Molex connector at the empty optical bay.
     
  20. Rankrotten macrumors 6502

    Rankrotten

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    #20
    This is my setup:

    - Bottom slot: Radeon 3870x2 fed from both PCIe motherboard power connectors (windows bootcamp only)

    - Middle Slot: Creative PCIe 5.1 soundcard (windows bootcamp only)

    - Top slot Radeon x1900 fed from molex splitter in optical bay and shared with superdrive and blu-ray drive

    Hidden from view is the ODD SATA cable running from beneath the fan into the optical drive bay.

    To use Mac OS X leave the monitor connected to the x1900 on startup. To use windows vista leave the monitor connected to the x1900 on startup then hold option key to choose vista and immediately swap monitor cable onto 3870x2 for windows startup.

    Vista uses both GPU cores in the 3870x2 and if I'm able to track down a Mac Ed 3870 it will replace the failing x1900 and will be crossfired to the x2.
     

    Attached Files:

  21. ungraphic macrumors 6502a

    ungraphic

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    #21

    Which mac pro are you using?

    I'm thinking of setting up a similar configuration, however, I already have an ATI 3870 Mac Edition, so im running everything perfectly fine in both windows and OS X.

    Theres a PC shop across the street from work that sells a PC Edition of the 3870 for only $105 (which is a steal). heres the link:

    http://www.pcvonline.ca/productDetails.aspx?prodID=6723

    I've got a 2007 Mac Pro with two of those 6pin connectors on the mobo itself, one being occupied by the 3870 Mac Edition.

    Would the addition of the Asus Radeon 3870, put into the second PCI slot allow me to use crossfire in windows and normal booting into OS X and Windows without any kind of fumbling around if my monitor is plugged into the Mac Edition 3870?

    Thanks!!
     
  22. Rankrotten macrumors 6502

    Rankrotten

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    #22
    Should be ok.

    I have the same Mac Pro 06-07 Model. Let us know how you get on.
     
  23. nanofrog macrumors G4

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    May 6, 2008
    #23
    You could get a 2 port DVI KVM switch. :)
    This one will do for switching the card output to the monitor. Just ignore the PS2 ports. ;)

    Could make life easier, and save wear and tear on the DVI ports and cables. :p
     
  24. Cindori macrumors 68040

    Cindori

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    #24
    Hm, aren't you using a pre 2008 mac? If so, you can only have 1 16x PCI port and crossfire will only give 4x to your second card : /
     
  25. Rankrotten macrumors 6502

    Rankrotten

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    #25
    x8 to second card using the expansion slot config utility.
     

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