Running two GTX-285's in one Mac...?

Discussion in 'Mac Pro' started by gdesignz, Oct 12, 2010.

  1. gdesignz macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #1
    I am running into issues with trying to run three LED monitors,two 24's and the new 27" apple LED's.As of right now I have both of them running off my GTX-285 and things are great.I of course had to third part the deal,good old Atlona and dial that in.For me to run another monitor,I have to install another card.I was very close to getting the 5870,I can't seem to find it for sale anywhere.Now I hear the 5870 has issues as well,so I am thinking about running two GTX-285's in my MacPro,I don't know if it can be done.I am not sure if there is another power input for the second card.If anyone has any info if this will work,or it won't work,or which card to get.I was thinking about getting two 5870's and running those and then I should be all set.

    thanks..
     
  2. pastrychef macrumors 601

    pastrychef

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    Sep 15, 2006
    Location:
    New York City, NY
    #2
  3. 10THzMac macrumors 6502

    Joined:
    Dec 17, 2007
    #3
    I bought an OTT PSU which sits on the top of my 08 Pro and for several months had a Mac 285 and a PC 285 working together. One was powered off the two internal connectors and the other came off the PSU. The Pc card has now been swapped for a GTX 480, which uses a 6 and 8 pin pair, unlike the 285 which was 2x6 pin. Other people suggested supplementary PSUs that could sit internally and other power re-routing from DVD bay and SATA areas - there are several ways of dealing with the power.

    You might have trouble sourcing either Mac or PC 285s now. I would hold off till month end to see if Mac Quadro 4000 appears if you want Nvidia card.
     
  4. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #4
    Call me crazy, but do you actually need 2 GTX 285's? You've got three displays, I'm assuming not all of them are doing crazy intensive 3D work at the same time. Figure out which monitor is doing the least intensive work, and put it on a GT 120, which doesn't require any extra power.

    FYI, two 5870s will have the exact same problem as the 285's, and are not technically a supported configuration. It's why you can't buy a machine from Apple with two 5870s.
     
  5. gdesignz thread starter macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #5

    I am a full time graphic designer/digital media person and I use all three monitors for my work.With that said,I need a set up that is going to work and work well.The 5870 is said to be able to run 3 monitors,2mini and one with a DVI input,I am not sure if that is true.Or should I sell my GTX-285 and get two 5770's and try it that way?So for me to run another GTX-285,I'd have to create another power source,either by using a splttter,or tapping into another source?

    Any positive help would be great..
     
  6. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #6
    Right, but depending on what programs you do, running two GTX 285's may not give you any advantage at all. Most graphics design programs don't use the GPU at all. If you're not using one of your displays for serious work, split it up onto a separate GPU. It'll cause the other two displays to have better performance.

    Two 5770's are the better option, running three monitors off one card leads to significant performance degradation.

    Remember, every time you add a monitor to a card, you're forcing it to start up a separate frame buffer and split up it's VRAM among the displays.

    Especially if you work in video editing, you're far better off to split off your displays onto separate slower cards, with one higher end card handling the heavy work.
     
  7. gdesignz thread starter macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #7
    Fast and eye opening response,thank you..? 4 U..Do you think I should get two 5770 video cards and run them and sell the GTX-285 then?I assume running the GTX-285 and one 577O would be a bad idea..mixing Nvidia with AMD isn't I assume.

    I am going to trust your call,right now I am all third partied out with Atlona and it's getting old..
     
  8. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #8
    Actually under Mac OS X and Windows 7 (not Vista), mixing ATI and NVidia should work just fine.

    You're still going to run into power constraints unless you start adding some custom solutions (like the drive bay power system linked to above), still, with the 5770 and the GTX-285. Your Mac comes with two GPU power connectors. The GTX-285 and 5870 both require all two power connectors. A 5770 requires one. You can work out the combinations from there. With the default power setup, you're looking at one GTX-285, one 5870 or two 5770's. The reason I brought up the GT 120 is because it is the only card that requires no power connectors at all, so you can add as many of those as you want with any card.

    Also, the 5770 is somewhat around the same speed as the GTX-285. It's kind of a mixed bag, but for professional apps, generally the 5770 will be faster than the GTX-285.
     
  9. gdesignz thread starter macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #9
    Out of the 5870 and getting two 5770's.Do you think I should just get two 5770's and call it a day..?

    let me know and thanks..
     
  10. 10THzMac macrumors 6502

    Joined:
    Dec 17, 2007
    #10
    I should probably add the motivation for loading two 285 GPUs was more to do some heavy CUDA work than to drive multiple monitors. If it were not for that I'd probably have a 120 and a 285, within the Nvidia options, for the reasons already stated above.
     
  11. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #11
    Heavy CUDA work is a totally valid reason... Although I'd note you could still do the same amount of work and avoid the power issues by loading up your machine with 120's.

    CUDA does not require the card to have an active display to be used, and it can use cards in parallel. So basically for CUDA you could just load up your machine with a bunch of cards, and it should automatically use them, even if there is no display connected. OpenGL is the only thing that cares which display is on which card and which cards are active.

    (For reference, I'm a CUDA programmer and I have this sort of setup on my Mac Pro at home.)


    Yep, if you're not doing CUDA work, this is the best setup without running a bunch of messy power wires through your machine and out the back.
     
  12. tomscott1988 macrumors regular

    tomscott1988

    Joined:
    Apr 14, 2009
    Location:
    UK
    #12

    Seen as tho the 5770 is the bottom range card, it is about the same speed as the 4870. The 285 is faster than both cards the 5870 is the only card faster than the gtx 285, hence why there is non to be found anywhere people snapped them up as quick as they could when the new mac pros were announced. Plus you have cuda support the the nvidia card, if you are using premier etc.

    People have been pissed that apple is only offering ati cards, i am one of those, the only reason in my mind to get rid of a 285 at this present time is if you want a new ACD, or if/when the 5870 becomes available.

    If you want a cheaper option the you can pick up 120 cards for about £60, not a good card but doesnt need any power supply, and if you are just running displays say running photoshop then thel be fine. If you feel you need more power the only option you have is to sell the 285 and buy 2 5770's. Seen as tho it is the only card currently available to purchase. Or you could make some make shift power conversion but i think its more hassel than its worth, you may feel later on you want to add another burner, (say blu ray) etc just a shame apple offers no competition in the graphics card department.

    To be honest for a professional workstation with the 5770 and gt 120 being only cards available to buy without buying a new machine is horrendous. Its unfortunate that they discontinued the 285 and 4870 and its pathetic they havent started selling the 5870. I wouldn't want to be someone looking to by graphics cards at the moment, i would definitely feel i was wasting my money.
     
  13. gdesignz thread starter macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #13
    I feel you there,I found someone who'd be able to get me a 5870.I was just told my apple that my macpro 4,1 wouldn't be able to run the 5770 cards at all.I am being forced to get another GTX-285,well try to get a used one on line.Then find another power source for it to work.I do a heavy amount of 3d animating,special effects,final cut pro use,avid,zbrush..the list goes on.If I want a blu-ray player or burner,I'll just get an external one.I don't know what the deal is with apple and why they make things so difficult for the non-average user..Thanks for your input..I didn't think the 5770 was even close to the GTX-285..
     
  14. gdesignz thread starter macrumors newbie

    gdesignz

    Joined:
    Oct 12, 2010
    #14
    I can work on getting another GTX-285 and make shift another power source,or wait and get the 5870.Which one would you stick with,two 5870's or two GTx-285 cards?


    this is what's it's come down to..apple really can cause you unwanted stress..
     
  15. 10THzMac macrumors 6502

    Joined:
    Dec 17, 2007
    #15
    I find this part a bit strange. The 120 has a tiny fraction of the cores of a 285. Unless you want to work out some complex GPU scheduling issues arising from say 3+ cards in one machine, I think the 240 cores of the 285 rather thrashes the 32(?) of a 120. On nbody for example a pair of 285s will run 2x480 GFlops in a pair of windows. Does the 120 even do double precision work?
     

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