5870 + Second card?

Discussion in 'Mac Pro' started by goMac, Nov 16, 2011.

  1. goMac macrumors 603

    Joined:
    Apr 15, 2004
    #1
    So a little background...

    I have a Radeon 5870 (Apple OEM) on my 2008 Mac Pro. I have apps that want an entire gig of VRAM to themselves for a single display, and I run two displays. So I need a second card to run a second display.

    I have been using a GeForce 120. It had been working great up until Lion. Now, with the GeForce 120 in the machine, I get severe performance degradation (Frame rates down by about 2/3). When I take it out, everything is fine.

    Are there any alternatives? I'm getting tired of this issue. As far as I know there aren't any ATI cards of similar power that don't require power leads.
     
  2. Neodym macrumors 65816

    Neodym

    Joined:
    Jul 5, 2002
    #2
    You could consider replacing your 5870 with a flashed 2GB version to drive both displays from one card. Alternatively switch from the Apple-5870 to a 2GB-6870, which seems to work pretty fine out of the box under Lion (so no flashing required) and draws less power while being only marginally slower than the 5870.

    Besides: Where do you see the hit in frame rates - on the GT120 or on the 5870? If it's the GT120, do you also experience them, when it's sitting alone in the Mac Pro (i.e. without he 5870)?

    It would also be helpful for giving advice, if you mentioned the resolution and applications you want to run on the second display (e.g. is 3D power required?).
     
  3. wa5655 macrumors member

    Joined:
    Jun 12, 2010
    #3
    Will a 2G-6870 be able to drive 2x27 inch displays under Photoshop? How will it perform against 2x5770 driving the same 2x27 displays?

     
  4. goMac thread starter macrumors 603

    Joined:
    Apr 15, 2004
    #4
    Does the flashed version have any caveats?

    I see them on the 5870 display. I haven't tried the GT 120 all by itself. It's a shame because it's the card where I care about performance.

    I do graphics programming, games, etc.

    Weird things happen when both cards are in the machine. The GT 120 suddenly reports having 1 gig of VRAM in the OpenGL Profiler, while the 5870 reports 512 megs.
     

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