Panther Freezes: It’s not the RAM

Posted by Pierre Igot in: Macintosh
August 17th, 2004 • 3:45 am

Following the persistent recommendations of a Betalogue reader, I went ahead and tested various RAM configurations in order to identify a possibly defective RAM module in my G4 MDD.

I have three 512 MB RAM modules: one that came with the machine from Apple, and two that I bought from Other World Computing, a usually reputable RAM vendor.

I took all three RAM modules out, dusted them, and tested them one by one, i.e. by putting only one RAM module in the machine and attempting to run the G4 on 512 MB, waiting for the machine to freeze.

I am afraid that I have to report that, in all three cases, i.e. for all three RAM modules used independently, I experienced a freeze within less than 48 hours. In other words, the situation was not any better than it was with all three RAM modules installed.

Unless all three RAM modules have suddenly become defective at the same time — which is rather unlikely, after they’ve worked for over a year and a half with no problems) — the conclusion is clear: It’s not the RAM modules.

Panther freezes regularly (and there are enough reports on to suggest that it’s far from an isolated situation), and the RAM is not at fault. The hard drives are not at fault either, since they have been replaced, to no avail.

I am afraid we are back to square one, i.e. to a strong suspicion that it’s a bug in Panther itself. The bug obviously does not affect everyone, and it seems to occur in specific situations, like heavy network activity or heavy hard drive activity or both combined. Since I am a heavy user of my machine, I tend to create such a situation fairly frequently, I guess.

It’s also still possible that the presence of third-party software and hardware precipitates the problem. I guess the only way to find out will be to do a clean installation of Panther on a separate partition and test that one for a while. It’s going to be pretty time consuming, but I don’t see any other solution at this point.

I also haven’t entirely ruled out the possible influence of heat. It might not be a coincidence that the number of freezes that I have been experiencing has risen sharply in the past few weeks, where the weather has been particularly hot and humid (nothing too severe by most people’s standards, but hot enough to cause my G4’s fans to switch gears on a constant basis, something that they never do in the winter time).

One final note: This morning, when I was still in the process of testing the last of the three RAM modules, when I woke up the computer it appeared to be frozen. Like the freeze I got last week and described here, the screens woke back from sleep, but their contents were stuck at 22:45, the time when the computer went to sleep last night. And there was no mouse pointer.

I thought it was a freeze — but then after 20 seconds or so things started responding again, gradually. I pressed the Mute key and 10 seconds later the sound came back on. The clock went back to the time of the day. It still took another minute or so, but finally everything was back in business. In other words, the computer got dangerously close to freezing, but then recovered somehow. Whatever that means.

Then earlier this afternoon I was typing a message and everything just froze solid — except for the mouse pointer. Impossible to SSH remotely into the machine. Nothing. Hard reset required. End of RAM test.

And the Panther freeze saga continues… It certainly is a major disappointment, especially as a long-time Mac OS X user who has been able, in the past, to enjoy extended periods of uptime with no disruption (weeks, sometimes longer!).

Everything seems to point towards an Apple screw up somewhere down the line. But where? It’s hard to report these freezes to Apple since we have no data/crash reports to send, and the circumstances are obviously very diverse.

Another recent reader seems to incriminate AirPort. I might try fiddling around with this to see if I can get any changes in behaviour. I can connect my G4 to my network via Ethernet instead (no big deal), but I’ll keep the AirPort connection on so that I can monitor it and reestablish it when it’s cut off. But my Ethernet connection will be the primary one. We’ll see if that changes anything. If not, I might disable AirPort completely, although it would make things inconvenient. (You can’t monitor or control an AirPort Base Station via Ethernet, unfortunately.)

14 Responses to “Panther Freezes: It’s not the RAM”

  1. Pierre Igot says:

    OK, I won’t put my entire system profile up on this site, because there might be privacy issues. But here it is in a nutshell:

    G4 MDD dual 1.25 GHz


    Memory: 3 DDR SDRAM modules of 512 MB each in slots 1, 2 and 3. Slot 0 is empty.

    PGI/AGP: AlchemyTV tv-card in PCI slot 5, ATI Radeon 9000 in AGP slot 1, 2 displays connected to it (1 23″ Apple Cinema Display HD, 1 17″ Apple Studio Display FP)

    ATA-3 Bus: 2 SuperDrives connected (1 Pioneer DVR-104 that came with the machine, 1 Pioneer DVR-107D added later on)

    ATA-6 Bus: 2 hard drives connected, one 120 GB Seagate hard drive with 3 partitions, including startup volume, and one 160 GB Seagate hard drive with 3 partitions. Both installed recently, the original IBM drive was taken out because it was suspected as possible cause of crashes.

    SCSI: nothing

    – USB plug 1 on G4: flash card media reader
    – USB plug 2 on G4: connected to Griffin USB audio hub
    – USB hub on 23″ HD display: 1 Apple Extended USB keyboard and 1 Kensington USB Mouse
    – USB hub on 17″ display: not connected, because doesn’t work reliably
    – USB hub on Apple Extended USB keyboard: not used

    On the Griffin USB audio hub:
    – 1 PowerWave USB audio
    – 1 Griffin PowerMate
    – 1 Canon CP300 printer
    – 1 M-audio MIDI keyboard (only when in use)

    – FireWire plug 1 on G4: external 80 GB OWC FireWire HD
    – FireWire plug 2 on G4: external 120 GB Kanguru FireWire HD

    On the OWC HD another external FireWire HD (small 10 GB HD in portable OWC enclosure) is hooked up. On the kanguru HD an external FireWire LaCie CD burner is occasionally hooked up (but shut down most of the time)

    AirPort: first generation AirPort card, firmware version 9.42, set to use channel 7, local network

    Modem: unused

    Network: connected to external AirPort Base Station (original graphite) via AirPort. ABS itself is connected to a wired Ethernet network and shares its modem connection to the Internet with both the wired and the wireless devices on the network, using DHCP.

    Extensions: see this page.
    Applications: see this page.

    Any questions? Just ask.

  2. brian w says:

    How about making a diagram/list of your exact setup for all of us to pick apart? I think the people who are reading your blog are as exasperated as you are.

  3. Paul Robertson says:


    All I can say is bugger! Thanks for trying my suggestion, at least I won’t keep hassling you to test the RAM :-)

    Looks like Panther’s the culprit after all.

    The partition idea seems good one.

    BTW My ibook saga continues – on my fourth logic board, and now the track pad has gone on the fritz and the cable connecting the LCD to the logic board appears to be about to break (on the the basis that the LCD’s picture moves an inch to the right when I shut the ibook slowly.) Back to Apple it will have to go, AGAIN, and I wasn’t sure buying Applecare was a good idea!

  4. MacDesigner says:

    Actually after reading all your blog posts through this problem. I have to lean towards the heat issue. Perhaps the connection between the processor and heat sink is faulty. Do any readers know of a monitoring system for the CPU.

    I had a classmate that had a problem with freezes. Turned out his heat sink had come loose during shipping. Perhaps yours is related. A second friend had freezes on her first generation iMac, she added a fan to increase the air flow and the freezes disappeared. The heat sink or the thermal grease between the CPU and heat sink could be causing the problem. While not immediately overheating perhaps it builds over time till it reaches critical mass. The only way to solve this of course is to take it to a service center where they can remove the heat sink reapply the grease and reattach the heat sink.

    While I feel the chances of this being the problem are low, it is not an impossibility. Similar to a wire in a car that is shorted out and causing intermittent stalls.

  5. LoonyPandora says:

    This problem has obviously been going on for a while, although it may seem like admitting defeat, I would book it into a local service centre. They can swap parts and leave it on soak test for days. That’s going to be the best way to figure it out – swap logic board, see if it fails, swap processor, see if it fails – if it is still failing after that, then you may be right.

    I was having a similar problem with a customers machine, and it turned out to be the ATA controller on the logic board which was faulty, symptoms were the same as yours, specifically, it was happening when the customer was running Azureus (Java BitTorrent client) – which puts a lot of stress on network and the HD’s

    If you are willing to give me the serial number of your machine, I would be happy to check the Apple-only kbase articles for any possible issues on that batch of machines.

  6. Pierre Igot says:

    Thanks for the advice. Obviously, before I can get my “local” service centre (300 km away) to even consider taking my machine in to have a proper look at it, I have to make sure that the problem can be reproduced pretty consistently. Right now, it happens on average once every 48 hours or so. Can I really expect someone at the service centre to use the machine until it freezes? Probably not. So I have to come up with a relatively sure-fire way of triggering the freeze. That’s when it becomes a bit challenging. Any suggestions?

    LoonyPandora: If you could contact me by e-mail using the form on this site, I could then give you the serial number. Thanks…

  7. Josh says:

    I had a client with this similar sounding issues. Swapped RAM, did clean install, the works. I knew to unplug all third party USB devices, leaving only the keyboard and mouse, in order to eliminate the variables. Crashes persisted. I was at my wit’s end.

    Then I replaced the keyboard (stock Apple.) Crashes went away.

    Worth a shot…

  8. George Fowler says:

    One way to distinguish betwen heat and Panther as the culprits would be to restart regularly, say once a day (i.e., before your freezes are known to happen). If this is some cumulative issue with Panther that worsens as time passes, eventually triggering a freeze, then these restarts should completely prevent this problem. And it only takes about 2 minutes to restart, not a fate worse than death. If, however, the issue is heat, the restarts won’t alleviate the problem, since they won’t cool off the system.

    I really think continuous uptime is overrated. Restarts clear out the swap files (though with so much RAM yours shouldn’t become all that onerous). On my system (Quicksilver G4 867, 1 GB RAM, lots of peripherals) the system is noticeably snappier when I have just restarted.

    Worth about $0.02 (Canadian).

    George Fowler
    gfowler AT indiana DOT edu

  9. Pierre Igot says:

    Josh: Will give that a try. Thanks.

    George: Continuous uptime might be overrated, but my machine definitely takes more than 2 minutes to restart! I have a fairly large number of startup items and they take a good 3 or 4 minutes on top of the 2 minutes required by the system. Then there are all the web pages I need to reload over my pokey 28.8 kbps connection. Restarts are definitely a waste of time as far as I am concerned.

    But I agree that regular restarts might enable me to further isolate the problem. However, I have already reported here that, in some cases, I experienced several freezes in the same day. I specifically remember experiencing one not long after a restart (within half an hour) not long ago. So it doesn’t seem to be a cumulative issue.

    Thanks for the advice…

  10. Jason says:

    I have been having crashes with my Dual 1.25 MDD also, so I decided to search for other reports, coming across this site.

    When I had my 3rd party keyboard’s drivers installed (Macally Icekey), there was a problem I noticed when starting in Single User Mode, where it had something about not loading some USB file properly, and then a pressed key would repeat like “ssssssssssssssssssssssss”, which would be resolved by unplugging and plugging in the keyboard. I don’t have the drivers installed, so that “sssss” problem hasn’t showed up.

    This computer also crashes in OS 9, so I don’t think it’s a Panther problem with my setup. Maybe you can try to use OS 9 to see if it crashes, also. In my case, I think it might be heat or the keyboard- or both! Or some other MDD motherboard problem. But also, this machine crashes when playing some games, which could mean cpu->heat, or the video card; I have the stock Radeon 9000.

    This thing is crashing more than back when I used to use OS 7.5, 8, or 9!

  11. Pierre Igot says:

    Jason: I’ve since been able to determine that my problems were related to the ATA bus (possibly a motherboard defect) and I eliminated the problems by moving my internal hard drives to the other ATA bus. Haven’t had a single freeze since.

  12. Jason says:

    Nice! Maybe I will try that. The crashes are driving me mad…

  13. Pierre Igot says:

    Mark: see my comment dated Oct. 9 above. Obviously, with a G3 iMac, there’s not much you can do if the ATA bus is involved. But it might be a completely unrelated problem in your case. Good luck :-/.

  14. Mark says:

    This freezing/crashing is happening on my iMac G3 400. It never did this with Jaguar. However, once I upgraded to Panther, it started exhibiting these issues.

    Have you resolved this issue on your computer yet?


    — Mark

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