2 Graphics Cards - Benefits?

Discussion in 'Mac Pro' started by astrobhoy, Dec 8, 2009.

  1. astrobhoy macrumors newbie

    Joined:
    Nov 25, 2009
    #1
    Hi All,

    I have a new G5 of which I have the following graphics cards fitted:

    ATI Radeon HD 4870
    NVIDIA GeForce GT 120

    the reason that I have 2 is that when I bought the HD 4870, Apple generously gave me the NVIDIA free with it.

    My question is:

    Are there any real benefits to me having 2 cards?
    Does it make any difference which card I have my 2 monitors connected to?
    If I have my monitors connected to the weaker card (NVIDIA) will it help free up the processing of the 4870? or vica-versa?


    I did have one monitor connected to each card, but this cause rendering problems in FCP6 (bug) so I had to remove, but I have a Mini displayPort to DVI adapter to connect the 2 monitors I have to one card. It's running fine just now, but seeing as I don't know the answer to those questions, I might not be getting the optimum useage out of them.

    Thanks in advance.
     
  2. iamcheerful macrumors 6502

    iamcheerful

    Joined:
    Oct 3, 2008
    #2
    astrobhoy, do you have a G5 powermac or do you mean the latest intel mac pros?

    I believe you mean intel mac pros.


    Are there any real benefits to me having 2 cards?
    Yes.
    Does it make any difference which card I have my 2 monitors connected to?
    Yes
    If I have my monitors connected to the weaker card (NVIDIA) will it help free up the processing of the 4870? or vica-versa?Technically yes, but in practice, you have to connect the display to the card in order for the card to be in use. I am not yet aware of applications taking advantage of the GPUs w/o having it being connected.

    Some of the applications I've encountered that does benefit from GPU ...
    - MovieGate
    - Pixelmator
    - iMaginator
     
  3. astrobhoy thread starter macrumors newbie

    Joined:
    Nov 25, 2009
    #3
    thanks iamcheerful! I am using my mac for graphic design photoshop/quark etc, but it's mainly the video stuff that pushes/tests it most - Final Cut Pro Suite etc. Do any of these use the 2 cards?

    Does the graphics card play a big part in rendering or processing times, or is it mainly just a display/quality thing?
     
  4. PaulD-UK macrumors member

    Joined:
    Oct 23, 2009
    #4
    Hi
    Do you use FCS 3/FCP 7?
    Versions of FCP up to FCP 6 won't work with FX-Plug effects when there are two graphics cards plugged in - you get an error message.

    I've heard reports that FCP 7 has been working with two nVidia GT 120 cards, but the persons doing it didn't know enough to recognize what an FX-Plug plug-in is, so I don't know if FCP 7 fixes things.

    If not you have to just go with the ATI 4870, which will give much better rendering powers with FCS.
     
  5. astrobhoy thread starter macrumors newbie

    Joined:
    Nov 25, 2009
    #5
    Hi Paul,

    no am still using FCS2 but am upgrading to FCS3 soon. Would be interesting to see if it does utilise the 2 cards though. Certainly the problems that I had were that it wasn't processing certin effects - sorted though as soon as I pulled the connection out for one of the monitors.
     
  6. Transporteur macrumors 68030

    Joined:
    Nov 30, 2008
    Location:
    UK
    #6
    Just make sure you connect you displays to the 4870. This card is way faster than the GT120.
     
  7. MrLatte23 macrumors regular

    Joined:
    Jul 18, 2007
    #7
    FCP 7 and Dual cards

    I have a Mac Pro 1,1 with a NVIDIA 8800 and 7300 in it. FCP 6 gave me problems with rendering any FX Plugins, so I disabled all of them. Everything works fine with FCP7 now. I have the better card in the primary slot of the computer running at full speed with 2 of my four monitors connected to it. Since it's the beefier card I make sure that any program or canvas windows from FCP display thru the 8800.
     
  8. gugucom macrumors 68020

    gugucom

    Joined:
    May 21, 2009
    Location:
    Munich, Germany
    #8
    The only reason to leave the 120 in the machine is the use of monitors that utilize more than the one MDP and one DVI on the 4870. Otherwise it will only suck power and do you no good.
     
  9. brock2621 macrumors 6502a

    brock2621

    Joined:
    Jun 8, 2007
    Location:
    Kentucky
    #9
    I haven't seen any performance increases with both cards. I have two cinema displays and am forced to have to cards because each card only has one mini display port. As far as final cut pro goes, i can only you both monitors if i lower the offline edit resolution to 1024x576 which is VERY annoying... I wish i knew how to fix it. If it's any other resolution, the preview monitor just displays a white screen.... :/
     

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