Dual GPU Problems on Lion

Discussion in 'Mac Pro' started by goMac, Jul 20, 2011.

  1. goMac macrumors 603

    Apr 15, 2004
    I've been running Lion for a while (developer) and have had an interesting problem that is still present in the GM builds, so I wanted to compare notes and see if anyone else has it.

    I have a dual GPU Mac Pro. One GPU is an Apple 5870, and the other is an NVidia 120.

    This config has freaked Lion out. It's confusing different elements of the two cards. For example, it seems to think my 5870 has 512 megs of VRAM. Frame rates have also suffered massively, it's running slower than my old 8800 GT when I'm running things on my primary display with my 5870.

    Has anyone else seen this? I'm going to crack open my machine tonight and yank the 120, but it means my VRAM is going to get halved from running both displays.
  2. matthewtoney macrumors regular


    Aug 17, 2009
    Charlotte, NC
    I actually had a very similar problem with Leopard/Snow Leopard on my 2009 Mac Pro (only it certain programs - it was like I had no acceleration at all)

    I asked around at the time and was told it was a bad idea to mix vendors. I had a ATI 4870 and the Nvidia 120 that came with the Pro so I replaced the 4870 with an Nvidia GTX 286 and sure enough all my problems went away. (and Lion seems to be fine as well with these two)
  3. goMac thread starter macrumors 603

    Apr 15, 2004
    Actually, I've never had this issue before. Works perfect on Snow Leopard and Windows 7.

    Lion? No dice. Got a bug opened at Apple.

    (In addition, I've seen 4870/285 GTX demo rigs from the Apple graphics team. And no, I don't know how they powered them.)

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