2x SLI GTX 590 in Mac Pro

Discussion in 'Mac Pro' started by freshface, Oct 4, 2011.

  1. freshface macrumors newbie


    Oct 17, 2010
    Hey guys!

    I have a mid 2010 3,3GHz Mac Pro (5,1 model). I would like to extend it with 2x SLI GTX 590 along with the default 5870. I want to use 5870 exclusively for OSX and 590s exclusively for Boot Camp Win 7.

    My question is, what are the issues any why do you think it will not work? I can probably work around the problems I already know, but I just want to make sure I don't miss anything. Mainly, will the 2GPU nvidia cards (GTX 590) even work in SLI with MP under Boot Camp? As I am not sure if the mobo has to have a support for something like that etc...
  2. voyagerd macrumors 65816


    Jun 30, 2002
    Rancho Cordova, CA
    I am pretty sure you would need an extra power supply, like an optical drive bay one. You might be able to get SLI using an SLI ribbon cable, however I cannot say for sure since I haven't tried it in a Mac Pro. Hopefully someone here has.
  3. freshface thread starter macrumors newbie


    Oct 17, 2010
    Yes, I will need an extra 600 (or so) W PSU. There is not enough power and cables in MP for two more graphics cards.

    I saw success stories with 2x CrossFire, but that's AMD, I would like to know if there is something missing in terms of hardware/software support to use nVidia's SLI.
  4. ActionableMango macrumors G3


    Sep 21, 2010
    There are lots of problems here.

    First of all, the motherboard is not SLI-certified. From (http://www.slizone.com/page/slizone_learn.html):
    Secondly, there are not enough slot brackets free. All three of those cards are double-slot, that's six external PCI brackets. MP only has room for 5 brackets. You might be able to overcome this if you convert one of the cards to single slot with a low profile cooler and single bracket.

    Third, you'd need an additional power supply and cables.

    Fourth, you'd need some way to remove the extra heat generated.
  5. freshface thread starter macrumors newbie


    Oct 17, 2010
    This info seems a bit dated to me:


    There definitely must be much more mobos with SLI support than that! To me it seems like some marketing bs - until somebody proves I am wrong.

    Additional PSU will be in an external case, probably "lian li qo8" along with these 2 graphic cards - they wont be inside the MP as there is no room like you said. Plus these things will get hot. I intent to connect the MP mobo with the external box via these very simple (hardware only, no software needed) 16x PCIe extension kits I found:


    There are 4 slots in MP. 2x16, 1x8, 1x4.

    So the setup will look like this:

    GTX 590 in 16x (extended to an external box)
    GTX 590 in 16x (extended to an external box)
    Radeon 5870 in 8x (there is only like 5% performance loss in 16x vs 8x)
    Some other card in 4x

    I would like to turn off the additional PSU which will power OFF the 2 additional cards and I HOPE that OSX wont recognize them so there wouldnt be any potential issues under OSX. Again "I hope", so please correct me someone who knows more about this. I just want to turn the external box ON once the Win 7 is booted.


    But yours is a Hackintosh? I doubt you have the same motherboard like is in Apple MP? Or do you? :)
  6. initialsBB macrumors 6502a

    Oct 18, 2010
    The "some other card in 4x" won't fit because the 5870 is double width, thereby taking up the space of the last slot.
  7. peskaa macrumors 68020


    Mar 13, 2008
    London, UK
    They're not wrong. SLI boards need to have extra chips on them to enable SLI, and they cost more for that very reason. The Mac Pro is not SLI compatible - it'll do Crossfire AMD cards, but only when using a Crossfire bridge.

    Yes, there are four slots, however some of the slots are only single width (i.e.: spacing between the slots on the logic board). As such, you can't fit four (or three!) double slot cards in. Physically won't go in the bay.
  8. ActionableMango macrumors G3


    Sep 21, 2010
    PCIe cards are powered through the PCIe bus. The external power provides supplemental power. I don't think turning off the external power will completely kill the cards. I've read elsewhere that a video card without the supplemental power will still work, but in a crippled mode. I don't know what a GTX 590 will do.

    Probably you should ask some of your questions in the Nvidia boards. They will know more about SLI motherboards and what a 590GTX does if it is getting PCIe power only.
  9. derbothaus macrumors 601


    Jul 17, 2010
    So the safer bet would be dual 6990's if power wasn't an issue?
  10. MacVidCards Suspended

    Nov 17, 2008
    Hollywood, CA
    Don't believe naysayers, SLI is doable in Mac Pro in WIndows 7.

    I have SLI'd GTX470s in Mac Pro, I have even Tri-SLI'd GTX285s in a Mac Pro.

    You use the SLI Hack and play around with Nvidia drivers til you find one that works.

    To run 3 cards, you ditch drives 2, 3 and 4 and remove bracket from card & BINGO there is space. (Where is TB when you need it?)

    GTX580 is supported in OSX...smart move would be to use them.

    Then you could SLI 2 of them in Windows, and use them as separate cards in OSX.

    I know you mentioned GTX590 but I don't recall if those have been tried in OSX. If so, it is likely that only 1 core shows up in OSX. Try reading up at InsanelyMac. They are using Hackintoshes for most part but they at least don't spend days pontificating possibilities from the safety of the couch and a Newegg catalog...they actually get the gear and TRY it out. (only way to get REAL answers) If it can be done on a Hack, it can PROBABLY be done on a Mac...though some of the details may change and you may have to turn your brain on and think for yourself a touch.

    You WILL need extra power. Newegg had something called Booster-X that worked pretty well...but you will need to drill some holes.

    Tri-SLI was not as big a gain as SLI since 3rd card had to go down in lanes.

    But I will say this, I tried Crossfire with 2 @ 4870s and Crysis felt a 20-30% increase in frames. (year ago or more)

    When I did SLI with 470's, I got around an 80-90% increase, scaled very well and much more effective. (2-3 months ago)

    The external solutions from Cubix & Cyclone are nice, but VERY expensive. And ultimately, they are using a software "magic trick" to stuff lanes where there aren't any so they do reach saturation at a point.

    Water cooling would get the cards down to single slot, but that is a whole 'nother engineering challenge with ZERO room for mistakes.

    The GTX580s can be made to work with just ATY_Init and perhaps adding device id to a kext or two.

    If you used GTX480s with EFI, you could avoid that bother.

    I'm not sure if I will ever figure out EFI for GTX5xx cards, much more involved than GTX4xx and nobody ever wants to help until you are done, then everyone is eager. (once the work is 99% completed)

    What it boils down to is how serious you are. If you have a wad'o'cash burning a hole in your pocket and some time, intelligence, and patience you can SLI some GTX580s for some serious power.

    If you have nothing but a desire to stir up the "It can't be done, now behave like the rest of the herd and live with the 3 GPU options the rest of us settle for" crowd, well, you've already done that, haven't you?;)
  11. ActionableMango macrumors G3


    Sep 21, 2010
    My mistake. Apparently there are no problems to overcome. Let us know when you have it working.
  12. Cindori macrumors 68040


    Jan 17, 2008
  13. MacVidCards Suspended

    Nov 17, 2008
    Hollywood, CA
    While this USED to be the site to come read about new stuff and try things, it has sadly become a place for curmudgeons to come complain about why you CAN'T do stuff.

    Read that older linked thread you posted. Even there, LOTS of armchair quarterbacking...lots of "know it alls" with many VERY good reasons why SLI won't work.

    They completely drowned out the voices saying "Yes, it can be done I'M DOING IT". (That little detail RUINED their theories...it had to go)

    Let the old men sit around and chew their cud and spit out more reasons people shouldn't try this. They seem to enjoy it.

    Galileo, Tesla, Einstein, Edison, Jobs...all famous for sitting around grousing about why you can't do stuff...

    Let the herd bleat. Why think & challenge when you can bleat? Here we are on this flat world with the sun spinning around us, what else is there to do?
  14. lloyd709 macrumors 6502

    Jan 10, 2008
    Not heard that before! Do they just work out of the box?
  15. cluthz macrumors 68040


    Jun 15, 2004
    Did you read what he said?

    Out of box ? no,
    easy? pretty easy
  16. The-Pro macrumors 65816

    Dec 2, 2010
    Interesting :) Ive been googling but cant find anywhere which explains how to make it work. Do you have any links which could help me to get on working in my 2009 8 core?

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