Windows won't recognise two graphics cards

Discussion in 'Windows, Linux & Others on the Mac' started by dryjoy, Feb 6, 2015.

  1. dryjoy macrumors regular

    Mar 19, 2009
    I've put a new EVGA GTX750Ti in my 2009 Mac Pro. I thought I'd put it in slot 1 and leave the original GT120 in slot 2, just in case I ever need to access the EFI boot menu.

    OS X was perfectly happy with this arrangement, but Windows 7 would only recognise the GT120 with both cards in. Just got a black screen from the new card, and no sign of it in any relevant control panel, DXDiag or whatever. After removing the GT120, Windows is fine with the GTX750Ti, but I would like to run both cards if possible. It was annoying, because by coincidence, I did actually have a disk problem which required accessing the EFI menu almost as soon as I took the GT120 out, so had to haul the Mac back out, put the GT120 back inside, sort the problem and then take it out again.

    Is there any way to get Windows 7 to play nice with both cards in the Mac Pro? It's not too much of a big deal but would prefer to have both in if possible.
  2. maflynn Moderator


    Staff Member

    May 3, 2009
    I wonder if its similar to how Windows cannot access the iGPU on MBPs that are equipped with dPGUs. Maybe something in the EFI that disables one of them on boot up.

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