Q: Mac Pro with 8800GT and GTX 280 - how do I make the GTX 280 primary in Vista?

Discussion in 'Mac Pro' started by StanD, Nov 12, 2008.

  1. StanD macrumors member

    Joined:
    Oct 15, 2008
    Location:
    Raleigh, NC
    #1
    Subject about sums it up!

    I have an 8800GT and a GTX 280 successfully installed in my new Mac Pro and they seem to work fine. In Windows I installed off of the 8800GT and updated to the latest drivers. I can see the GTX 280 in Device Manager as well. No errors, no warnings.

    Now I have the video cards hooked into my 30" via a DVI-D KVM, and the plan was to make the GTX 280 the primary under Vista and just toggle to it upon boot. For the life of me I can't seem to get this to work!

    I tried disabling the 8800GT but that just leaves me with black screen for both cards, whoops :) A quick trip to Safe Mode fixes it.

    What am I missing here? I've searched the forums and have seen others do it so I figure I am missing something simple.

    To those of you with multi video cards in your machine, using one for each OS: HELP!

    Thanks in advance,


    - Stan
     
  2. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #2
    Once in windows, and into the device manager, you might want to uninstall the 8800 rather than disable it. It should force it to use the GTX280 as the default, AFAIK.
     
  3. StanD thread starter macrumors member

    Joined:
    Oct 15, 2008
    Location:
    Raleigh, NC
    #3
    Hey nano!

    Just tried this and it blew away my Nvidia driver software even when I told it not to. Didn't work either. The damn card is there and I can see it but for the life of me it won't let me use it as the primary display adapter. GRRRR.

    This is very frustrating!!!


    - Stan
     
  4. StanD thread starter macrumors member

    Joined:
    Oct 15, 2008
    Location:
    Raleigh, NC
    #4
    Follow-up:

    Since it seems I've lost everyone but nano on this I will post the solution for posterity sake in the hopes that a future person with the same problem will have luck with a good ole STF.

    So the problem stems from the fact that the two cards are hooked into a Belkin Flip DVI-D KVM into my 30" LCD (one DVI-D port). Now when you have it set to use the 8800GT and boot into Windows it will "see" the two video cards per se but will only enable multiple displays IF THEY ARE POWERED ON! This is the clincher.

    In the case of a KVM (and not for a multi-monitor setup) it will report there is no display and so Windows will think you have that other display off and display multi-monitor support completely. How nice of them.

    The only way I ended up making this work was to go get another monitor (!) and plug it into the GTX 280. I then booted Windows and set the primary display to the GTX 280 and rebooted (and rebooted, and rebooted...). After several reboots and some praying I had the GTX 280 as the primary ONLY AFTER Windows started. It still shows the Windows loading screen on the 8800GT then switches over to the GTX 280 after Windows starts. Weird.

    Anyways, I hope this proves useful to someone out there. I do wish Windows wouldn't try and be too "smart".


    - Stan
     
  5. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #5
    I didn't know about the KVM switch. :eek: :p

    That was definitely a weird issue. I'm glad you got it sorted. :D

    Hopefully, the post might save someone else major aggravation. :)
     
  6. 10THzMac macrumors 6502

    Joined:
    Dec 17, 2007
    #6
    More details please

    Hi Stan

    Can you tell us

    (a) exactly which 280 card you have and what power cables you used for this combination

    (b) Whether you have had any luck getting the 280 to work under any version of OS X (including Snow L if you have access)

    (c) Have you programmed CUDA on it via either Windows or OS X
    Ta
     

Share This Page