G4 MDD locks up in the 1st few mins, normally with a very high pitched whining noise.

Discussion in 'PowerPC Macs' started by Diamond Dave, Aug 17, 2011.

  1. Diamond Dave macrumors member

    Nov 25, 2008
    Edinburgh, Scotland, UK.
    Over the last few months my Mac has developed a worrying habit.

    Within the first few minutes of starting it up (perhaps on average about 50% of the time) it will completely lock up. This may happen at the Log In screen (if I start up the Mac & then leave it for a while) or during normal use.

    Often the first symptom is a very high pitched (but quiet) whining noise that seems to come from the loud speaker on the front of the Mac. The pointer may freeze at this point, or it may still be moveable for 5 or 10 seconds before it freezes. It sometimes turns into the spinning beach ball during this. Once locked up the only way I can restart the Mac is to hold down the power button on the front for a few seconds to completely reboot the machine.

    Once the Mac has restarted, it usually behaves normally, almost always for the rest of the day. The initial lock up & resulting restart only normally seem to happen the first time I use the Mac that day.

    The only peripherals attached to the Mac (apart from the display, keyboard & mouse) are an ADSL modem, a USB printer and a pair of Apple Pro speakers, and this setup hasn't changed since long before the problems started, so I'm confident that I can discount the peripherals causing problems. I doubt that unplugging the speakers, for example, would have any effect.

    I've run Disc Utility, OnyX and DiscWarrior without anything major cropping up. My instincts (I've been troubleshooting Mac problems for 16 years) tell me that I have a fundamental hardware problem, possibly with one of the 4 RAM DIMMs installed.

    The RAM configuration is shown in the attached screen grab.

    System Profiler screen grab.jpg

    I'm considering removing one DIMM, running with 1.5GB of RAM rather than 2GB for a while, and repeating with a different DIMM removed each time until I can hopefully isolate the dodgy DIMM.

    Do people feel this is a sensible approach, or should I try something else first?

    Many thanks.
  2. ThunderSnake, Aug 17, 2011
    Last edited: Aug 17, 2011

    ThunderSnake macrumors 6502

    Jul 23, 2010
    Which MDD? Which OS?

    Do you have Temperature Monitor installed? What's the temp?

    Are all of your fans running? When you open it to find out, see if you can narrow in on that whining noise.

    Does it happen with a safe boot?

    Does it happen when booting from CD?


    Ooops. Totally missed that sentence the first time around. Weird. I'm thinking you're right that it's hardware. Maybe something with an aging moving part not wanting to make a cold start? Fan motor? How old is your hard drive?
  3. ThunderSnake, Aug 17, 2011
    Last edited: Aug 17, 2011

    ThunderSnake macrumors 6502

    Jul 23, 2010
    See if you can isolate that noise. Just behind the speaker are two fans in the PSU. Electric motors can make a whining noise when they're on they way out or when they're blocked. You can examine them visually with a dental mirror to see if there is dust buildup. Also, an automotive stethoscope (less than $10 from your local parts store) can be REALLY handy for this sort of troubleshooting work.

    If you like this Mac and want to keep it around for a while longer, now might be a good time to do a full tear-down for cleaning purposes. You really need to take out the PSU and open it in order to clean it. Don't touch anything on the inside, though. Capacitors will still be holding an electrical charge even unplugged. Just take the cover off and blow it out with some compressed air.

    Speaking of capacitors, they can also make a whining noise.
  4. Diamond Dave thread starter macrumors member

    Nov 25, 2008
    Edinburgh, Scotland, UK.
    Thanks for the advice.

    I initially posted this topic over at the Apple Support Communities Discussions, and over there the spec. of my Mac is automatically listed at the end of every post. I just copied & pasted from there to here, and forgot that I needed to mention the spec. here.

    It's this Mac - a Power Mac G4 Dual 1.25GHz (Mirror Drive Doors, no FireWire 800, Model No. M8570), running Mac OS X 10.4.11, with 2Gb RAM, a 1.5TB SATA internal hard drive, & the ADC version of the 23" Cinema HD Display. The hard drive is one of these (the now discontinued WD15EADS) connected with a Granite Digital SATA Drive to IDE Bridge Board.

    I don't have Temperature Monitor installed but I'll download & install it & see what it reports. I've not tried a safe boot or booting from a CD yet either.

    I like the Mac and I suspect I'll be keeping it for a long time as I can't afford a replacement. When I removed the old hard drives & installed the current one (just over 2 years ago) I gave everything I could see a wipe & a good blast with an aerosol of compressed air. Regardless of what Temperature Monitor says, and whatever the results of booting in safe mode or from a CD, I think it would be a good idea to give the Mac a very thorough internal clean from what you're saying.

    Having said that, the pitch, volume, duration & rough location of the noise sounds more like something electronic rather than mechanical to me.

    My hunch is that capacitors might more likely be the culprit. This is what someone over at the Apple Support Communities Discussions reckons too - see here.

    Many thanks for your advice. When I've investigated further I'll report back.
  5. ThunderSnake macrumors 6502

    Jul 23, 2010
    You're in good hands with BDAqua over there. He has been around for a long time. Japamac, another regular, has a MDD PSU Troubleshooting Guide that you hopefully will not be needing in your near future.

    And if it's never been done, a fresh application of thermal compound on the CPU would be a good idea. Temperature Monitor can be really helpful and provide a quick alert when something goes wrong, though. It saved my video card a while back. The AGP slot is so close to the CPU sensor that it picked up on the fact that the fan stopped working on my Radeon 9800.

    Interesting choice. It was wise to go with the adapter for the Green drive rather than the more expensive PCI card. On the ATA 100 bus, there is almost no difference in performance. From my own benchmarks with the same WD15EADS drive, the difference was less than 5%.

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