two video cards over one - performance

Discussion in 'Mac Pro' started by kunia, Jan 10, 2011.

  1. kunia macrumors regular

    Joined:
    Oct 30, 2010
    #1
    I didn't get any responses to my previous posts, so I'll ask again.

    I currently got the 5870 driving a 30" ACD and 23" ACD.
    Would there be any noticeable performance increase if I were get the gt120 to run the 23" and have 5870 run the 30" ACD (my work display)?

    adrian
     
  2. peskaa macrumors 68020

    peskaa

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    Location:
    London, UK
    #2
    Pretty much no. I have a 5870 running the 27" ACD and a 1080p Dell with no performance issues, and splitting the smaller monitor off to another card won't achieve any obvious difference.
     
  3. Hellhammer Moderator

    Hellhammer

    Staff Member

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    Finland
    #3
    The performance on the 30" would increase while the performance on the 23" would decrease. Depends what you do but I would leave it as it is. I remember Transporteur saying something about poor performance when moving windows to the monitor attached to GT 120 (IIRC he has 30" + ~23" hooked to ATI 4870 and ~23" hooked to GT120).
     
  4. goMac macrumors 603

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    Apr 15, 2004
    #4
    Depending on the application, you should see a performance increase. VRAM heavy apps will have 1024 megs of VRAM available instead of 512, which would lead to performance increases.

    I run the 120+5870 setup at home. Works great, and I can push the full gig of VRAM to SC2 to run in ultra mode.
     
  5. alust2013 macrumors 601

    alust2013

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    #5
    There may be slight improvements in some areas, but the 5870 is powerful enough that it should be able to run both without issue.
     
  6. goMac macrumors 603

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    Apr 15, 2004
    #6
    I'd say mostly it's a VRAM requirements issue. Using two displays on the 5870 drops you to 512 megs of VRAM. If you want that full gig available, you need the second card.
     
  7. alust2013 macrumors 601

    alust2013

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    #7
    Ah, that's a good point, I wasn't really thinking about the memory issue.
     
  8. Transporteur macrumors 68030

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    UK
    #8
    Copy that. But then again, this ONLY applies for running video applications. Windows showing static information are smooth as butter. There is another user here who basically had the same setup (20, 30, 20 PLP) with the same graphics cards and experienced the same issue (can't remember the same, sorry)
    After switching all displays to a single 5870, everything was smooth.
    Basically it seems as if OS X can't handle the interaction between different graphics cards very well. I'm not sure whether this issue is only related to the 4870/GT120 combination or to other cards as well.

    However, connecting three displays to a single 5870/5770 splits the VRAM to 333MB per display, which might be an issue for graphics related work.
    For my part, the 5870 will be on order once active single link DVI adapters become available in the UK. ;)
     
  9. kunia thread starter macrumors regular

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    Oct 30, 2010
    #9
    Any transition problem when you move windows between screens?
    The 23" on gt120 would run stuff like finder, browser, etc. I don't use it any serious work. Everything I do, Aperture, LR, photoshop, indesign I do on the 30" ACD - the 23" might for example run pages and iTunes.
    I do notice a slight "lag" when I play wow in windowed mode on 30" acd, while having an avi movie playing on the 23". Back with my old mac pro and 8800gt it was very noticeable under same circumstances, or when I've split screen either with lightroom or aperture.
     
  10. goMac macrumors 603

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    Apr 15, 2004
    #10
    I've see iTunes videos get a wee bit choppy when I move them between screens. Besides that, no.
     
  11. kunia thread starter macrumors regular

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    Oct 30, 2010
    #11
    one more thing:)
    in what slot is the gt120? any temperature/heat issues? and does it cover the 5870 fan?
    hmm...3 things:)

    thx
     
  12. goMac macrumors 603

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    Apr 15, 2004
    #12
    I believe I have mine in slot 2, right above the 5870. The 5870 is significantly longer, so it's fan is not covered by the GT 120. No heat issues.

    Edit, picture:

    [​IMG]
     
  13. kunia thread starter macrumors regular

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    Oct 30, 2010
  14. macz1 macrumors 6502

    macz1

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    Oct 28, 2007
    #14
    With a 4870 and 2600XT combo, (each card one monitor) I have no problems. Only if I play a movie streched across both screens it gets choppy if it exceeds a certain size.
    I didn't notice any annoying issues during normal work.
     
  15. kunia thread starter macrumors regular

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    Oct 30, 2010
    #15
    I'll be getting the gt120 from my local Apple Store.
    Just one more question.
    Having gt120 run the 23" monitor only, I'm assuming I'll have no problems running a MDP to HDMI to my TV. Would it carry audio?

    thx.
     
  16. Transporteur macrumors 68030

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    #16
    Your assumption is correct, but it won't have audio. That feature is only supported by the 5770/5870 in the 2010 Pro, or under Windows with all Mac Pro versions.
     
  17. kunia thread starter macrumors regular

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    Oct 30, 2010
    #17
    Ohh well..my TV build-in speakers suck anyway, and having TV connected to my MP is really not my main concern - I rather stream stuff through PS3.
    I'm hoping (there's no definitive answer, so I'm just hoping) for better performance out of the 5870 with just the 30".
     
  18. Transporteur macrumors 68030

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    Nov 30, 2008
    Location:
    UK
    #18
    Well, since you already have the hardware, why don't you just unplug the 23" and see for yourself?

    Personally, I don't notice any difference when I unplug my 20" from the 4870 and drive the 30" alone, but than again, I don't do any graphics work.

    Recommendation: Try before buy!
     
  19. kunia thread starter macrumors regular

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    Oct 30, 2010
    #19
    true...it does sound retarded:)
    Here's my logic...I wanted to get my TV running through HDMI at some point...but all those dual link dvi MDP adapters and then splitting the vram into 3 didn't sound very appealing. I'm pretty much basing this purchase on my old mac pro 1,1 with 8800gt and the same monitor configuration. Having lightroom run on the 30" display full-screen was a bit choppy...having an avi play on the 23" with LR was pretty much a no-go...Having LR run on the 30" display but scaled down with nothing on the 23" was much better, but having LR run on just the 23" (with 30" disconnected) was blazing fast...Same applied to Aperture. I never maxed out my CPUs or the RAM.
    I actually noticed the same on my current setup - this is most noticeable when running wow and having a movie play on the 23". And when people say they can run SC2 and Wow on maxed settings with 5770 and gt120...well, I can't have wow running on ultra with just the 5870, fps just drop to much.
    I'll be honest, ever since i got this mac pro, the video card never impressed me. It's way ahead of the 8800gt, but I was not expecting any noticeable and annoying hiccups. Besides, 2 x MDP to Dual DVI vs a video card for 170$...I rather get the video card. And if it all sucks, I'll just return the gt120 with no restocking fee:)

    I rather get the video card, work with it for about a week or so, get the feel for the setup and see if it's any beneficial, than try to test stuff with monitors connected/disconnect, this app, that app in this situation with that on and this off...etc, etc.
     

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