9 Replies Latest reply: Oct 15, 2008 8:10 AM by ansley.busch
Frank Huddleston Level 1 (5 points)
I have a PowerBook G4 which started to make low "grinding" noises when it worked hard. It had done this for maybe a couple of months: sometimes the position (on lap or on table, etc) seemed to affect it. I always figured it was the fan(s). But a little while ago it suddenly started making a loud buzzing noise, like a fuzz-tone electric guitar or maybe an electric razor. If I put it to sleep the noise would start, and it would not start immediately upon re-awakening. I'm not really sure where the noise was coming from. Otherwise the computer was still functioning normally, so I figured a fan was going bad. Then it just froze, and I had to turn it off. Upon powering on, it got to the point with a gray screen, an Apple logo, and a bar that spins in a circle. Never more than that. I've booted the install disk and run Disk Utility: it found some big discrepancy, in a file allocation I think, but fixed it. Since then I've repaired and verified: disk appears OK. I've run the hardware tests and everything tests OK. I can also get the terminal by booting from CD 1, and can do directory listings of the disk contents. So the disk seems to be OK. I removed the suspect fan: the left one, and looked at it. Aside from some dust in the filter it looked and spun fine, as far as I could tell.
Upon booting in "verbose" mode, I get the following:
member [46]: dsFindDirNodes returned - 14071, count = 2147483646
member [46]: Couldn't find root user. Sleeping and trying again.
These two lines just repeat...
I've got two questions here:
1) What should I do to get the computer operational again? Is there a netinfo restore I can do, or should I reinstall the OS (10.4) from the install disks?
2) How can I find out what caused the original problem?

Frank Huddleston

G4/400 AGP, PowerBook 15" G4/1.67MHz, Mac OS X (10.4.11), 100 GB 7200 RPM disk
  • eww Level 9 (52,980 points)
    Hi, Frank. Now that the computer won't start, at least not from its hard drive, are you still able to run the Apple Hardware Test that came with it? If so, what does AHT report now?
  • Frank Huddleston Level 1 (5 points)
    Yes, I've run the Hardware Test: the quick one once, and the extended one twice: once before I took it apart to examine the fan, and once after. Everything checks out OK.


    Frank H.
  • eww Level 9 (52,980 points)
    Frank: You can't always completely trust AHT when it finds nothing wrong — it's been known to overlook things sometimes. But assuming for the moment that it's right about your machine and there's no hardware fault, the next thing to try is probably reinstalling the OS. If all the important data on your hard drive is already backed up somewhere else, use the Erase & Install option. If there's un-backed-up data on the drive, use the Archive & Install option (that's IF you have enough free disk space for another OS installation in addition to the existing one. You should never have less than 5-10GB of free space on your drive at any time, including during and right after an Archive & Install. Many folks will say never less than 10GB. The more the better.)
  • cornelius Level 6 (17,825 points)
    1) What should I do to get the computer operational again?

    I have a strong suspicion that your HDD is failing. The average life of a modern HDD is 3 - 5 years, and 1%-3% fail in the first year. Even if the S.M.A.R.T Status comes up as Verfied (and I did not notice that you reported on that), it can still be failing. AHT needs to be run in a loop (Command + L during the tests) for several hours to pick up intermittent problems. When you hear the noises again, put your ear to the computer and try to identify the location of its origin.

    Even if you HDD is fine, eww's advice to backup is sound. You should have a backup anyway, but it is critical when you are having issues that may well be your HDD. Next, I would start shopping for a new HDD. For a list of available HDDs and online vendors, please post back.

    Incidentally, OS X needs a minimum of 5 GB of avaialable capacity (free space) on HDDs of 40 GB or less and a minimum of 15% on HDDs over 40 GB. Running with less than this risks serious directory issues, consequential loss of data and possible HDD crash.

  • Frank Huddleston Level 1 (5 points)
    Thanks for the replies. I have not heard the loud "buzzing" noise since (of course I have not used the computer as much), but I have heard the low "grinding" noise, and it seemed to me that it was coming from the upper left of the lower case of the PowerBook: right where the left fan is. I didn't hear anything much from the center, where the disk is.
    But of course I guess I can't rule out some sort of disk failure: obviously the lockup affected the disk.
    I'd like to test the disk more: aside from doing the cmd-L when the AHT is running, can anyone recommend a disk exerciser/tester?
    I tried restoring my netinfo database, using the instructions in
    but it didn't help: I got the same message from memberd.
    So I finally just copied a bunch of stuff off the disk in single-user mode and reinstalled Mac OS X. I
    archived the old system. So far, so good, but of course, I still haven't found out what caused the failure. I suspect that the "low grinding" noise is normal. Is there a way to see how the fans are doing via sofware? Is there some kind of test software for fans?


    Frank H.
  • BGreg Level 6 (17,495 points)
    Is there a way to see how the fans are doing via sofware? Is there some kind of test software for fans?

    The Apple Hardware Test does test the fans, you should hear them go one when tested.

    The free istat pro widget is good to tell you when the fan(s) are on and at what speed they are spinning. So when you hear the sound you could check to see if they are on. Download from http://www.islayer.com/index.php?op=item&id=7
  • Frank Huddleston Level 1 (5 points)
    An update: I have reinstalled the OS, and all my user files were still there in Previous Systems, so I lost no data. The noise has recurred a few times, and I listened for its location: it really did sound as though it was coming from the upper left. No system freeze, though: the noise stopped on its own after the period of intense cpu activity finished. I have checked the disk with the Disk Utility, and it verifies (I did not do this in single-user mode, however). So far, so good: it looks as though my left rear fan is going bad.
    Could that somehow cause the system lockup? If maybe the system temperature reached a high point?
    I have installed the iStat widget and have looked at that when I hear the low "grinding" sound, and it shows the left rear fan running at about 1740 rpm. But the right fan is at 0. Is this normal?
    The Apple Hardware reported no errors: I guess that means both fans are at least operational enough for the test. But what will make the system use the right fan as opposed to the left? Is maybe the right fan not coming on, then the left fan has to work too hard, and so now is failing? I have no idea what a "normal" rpm is for those fans.
    Also, at this point maybe this topic is more suitable for another forum. If so, please advise.

    Thanks for any help you(all) can give me.

    Frank H.
  • Frank Huddleston Level 1 (5 points)
    Another update: iStat reported the left fan going as high as 2400 rpm, but I never
    saw any activity on the right fan: always 0.
    The noise started, however, and I was able to check the fans while the noise was
    going: the left fan was running at only 143 to 300 rpm! Right fan was still 0.
    Temperatures for cpu bottom were going up: 54 - 56 Cent.
    For cpu top: 68 to 73 degrees Cent.
    For Power Supply: 62 to 64.
    No freeze-up, though: I put the computer to sleep at that point.
    So: it really does look as though that left fan is going (or is) bad.
    However, what's with the right fan? Should it be 0 like that? Does it handle some other devices or part of the computer's internals, which didn't need cooling at that point?
  • ansley.busch Level 1 (0 points)
    Hi Frank,
    This exact issue has happened to me as well--except I know VERY little about computers and am unsure about how to fix it. What exactly did you do to fix it? Your help is much appreciated!!