iMac PCIe Bus running at x1 instead of x16

Discussion in 'Windows, Linux & Others on the Mac' started by topgunn, Jan 20, 2010.

  1. topgunn macrumors 65816

    topgunn

    Joined:
    Nov 5, 2004
    Location:
    Houston
    #1
    Here is the situation. When I boot into Windows, my PCIe bus is changed from x16 to x1. When I reboot and load Mac OS again, it is still x1. When I reboot again and go back in to Mac OS, it is finally back to x16.

    I have tested this with WinXP, Vista, and Windows 7. I have tested this with the Apple drivers from the Leopard DVD, Snow Leopard DVD and the latest drivers from nVidia.

    At first I thought it was because I was loading games and stressing the GPU. Then I noticed it did the same thing without running any 3D games at all. Next I thought it was a temperature issue. So I installed SMC fan control and revved the fans up to max speed and rebooted in to Windows. The fan settings stuck as expected. I rebooted into Mac OS and the PCIe bus was again set to x1.

    I am at a loss. My best guess is that this is a firmware bug of some sort. I highly doubt it is because of the OS or driver version due to all of the combinations I have tried. Any ideas?

    Also, if it is hardware or firmware based, will Apple even do anything about it? Windows still "works" but just with a very slow GPU.

    Curious to see what you all think.
     
  2. topgunn thread starter macrumors 65816

    topgunn

    Joined:
    Nov 5, 2004
    Location:
    Houston
    #2
    Any ideas? Do you think Apple would do anything about this?

    By the way, this machine has had the logic board and graphics card replaced at different points since I have had this computer. The problem existed both before and after these parts were replaced.
     
  3. topgunn thread starter macrumors 65816

    topgunn

    Joined:
    Nov 5, 2004
    Location:
    Houston
    #3
    I have now had a case open with Apple about this problem for more than 3 months. They wanted to duplicate the problem in-house but I was told that they don't have an iMac with the 8800 video card. I haven't had an update in close to 2 months. Any ideas on what to do from here? How can I get something done to fix this issue?
     

Share This Page