2 Replies Latest reply: Jan 5, 2014 4:02 AM by Klaus1
vlhofmann Level 1 Level 1 (0 points)

HELP! How can I rest my USB Ports via system mangement controller? The ports stick to USB 1.1, though they are 2.0. reset of P-R and NV-RAM does not help.



PowerBook G4 (12-inch 1.5 GHz), Mac OS X (10.4.11)
  • K Shaffer Level 6 Level 6 (11,610 points)

    The method of resetting the 'power management unit' on an older powerPC based Apple Macintosh computer and portable computers varies from what the later intel-based models, since the PMU requires different steps and though some similar processes or items may be affected by the reset, there are different parts inside.


    Certain models of Apple portables of the PPC era have detailed methods for each, so here is an archived page of how or what to do with the PowerBook and iBook models. A list of each kind is linked to other pages on how to reset the Power Management Unit or PMU in the respective ones.


    • Resetting PowerBook and iBook Power Management Unit (PMU)



    The issue with USB1.1 and USB2.0 these may be in hardware, or may be in firmware. So it is a matter of attempting to troubleshoot, to find if the problem is a defect in hardware or some firmware glitch. Where did the system show these ports to be USB1.1?


    +You could also try a PRAM reset in another way, if the NVRAM/PRAM information you used didn't appear to do anything; but it may have worked. The other way is based on using Open Firmware, as follows:


    "Try resetting the PRAM through Open Firmware:

    Boot Mac while simultaneously holding Command+Option+O+F

    When at the command prompt type the following:

    reset-nvram <Enter>

    reset-all <Enter>

    The Mac should now reboot into OSX with a reset PRAM.

    You could also remove the RAM chip, & try restarting...." - ifixit.


    Hopefully this helps somewhat.

    Good luck & happy computing!


    {edited to add O.F. reset info}

  • Klaus1 Level 8 Level 8 (46,955 points)

    Probably also applies to a G4:


    Resetting the SMU on a G5 iMac:




    and on resetting the PMU on a Power Mac G5, G4 and G3 :