3D performance suddenly sucks, PCI Express Link Width stuck on 1x

Discussion in 'MacBook Pro' started by LoneWolf121188, Jan 26, 2008.

  1. LoneWolf121188 macrumors 6502a

    Jun 7, 2007
    Longmont, CO
    I was running Flight Sim X on my MacBook Pro (running Vista) last weekend after doubling my RAM (4GB FTW!) and everything was going great. I noticed a HUGE increase in speed, and I was able to pull 25fps or so with most settings all the way up. Life was good.

    Three days later, I boot back into Vista to do some more simming. Don't mess with anything, just load FSX after Vista finishes loading up. I run the exact same mission that I was doing before...and everything just grinds to a halt. I was getting literally <2 fps. WTF? I reboot, thinking its some random weirdness. Lo and behold, it does it again. I check everything in the nVidia control panel, power management settings, everything I could think of. Nothing changed.

    After some help from another forum, I realized that my PCI Express Link Width is stuck on 1x and won't throttle up when needed. Not having a BIOS to work with, how can I change this manually or otherwise force it back up to 16x?
  2. Listed1ST.com macrumors newbie

    Feb 2, 2008
    1st Step

    I'm not imagining that this will solve you problem, but hopefully it'll start you off on the right track.

    There is a utility to adjust the bandwidth allocation on the Mac Pro

    In system/library/coreservices you will find "Expansion Slot Utility"

    This brings up a window on the Mac Pro to choose which slots get what bandwidth. Dunno if it'll do anything on a MBP.

    Good luck!:apple:
  3. xraydoc macrumors demi-god


    Oct 9, 2005
    How is 3D performance when booted into MacOS X? Is the slow performance a Windows thing or does it also affect MacOS X? If its just Windows, might then be a corrupted driver or something. I'm not an expert at registry diving, so a reinstall (of Windows) may be in your future.
  4. LoneWolf121188 thread starter macrumors 6502a

    Jun 7, 2007
    Longmont, CO
    I don't have any Mac programs that are particularly graphics intensive, so I don't really know. What I do know is that if I go into System Profiler, I see 1x under PCI Express Link Width instead of 16x, so I assume that my 3D performance in OS X is also poor.

    I tried running it and I got an error: "Expansion Slot Utility is not intended to run on this system." Thanks though.

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