September 5th, 2006 • 11:38 am
Here’s the latest instalment of my latest hardware saga involving a Power Mac G5 Quad bought in November 2005 that started freezing on a more or less daily basis some time in August 2006.
As indicated in my previous posts on the topic, I was able to quickly eliminate USB and FireWire peripherals as potential culprits. Once that was done, I started suspecting my RAM modules. As far as I know, RAM modules can become defective after having worked without any problems for months or even years. It might be unusual, but it’s not unheard of.
So I tried to determine which RAM module might be defective. The G5 Quad came with 2×256 MB of RAM, and I added 4×1 GB of third-party RAM to it when I bought it back in November 2005. (I didn’t have any problems with frequent freezes or kernel panics until August 2006.) The RAM modules have to be installed in pairs in the G5 Quad, so the testing was a bit more challenging than it might have been on another model.
Here is what I have been able to establish.
- I have twice run the G5 Quad with only the 2×256 MB of RAM that came with it for extended periods (several days) without experiencing any freezes.
- I have run three lengthy passes of the third-party utility memtest in single-user mode with three of the four 1 GB modules installed (with modules 3 and 4, and with modules 1 and 3), and in both cases the RAM modules passed the tests with flying colours. I have yet to run the tests with module 2 installed in one of the slots, but at this point I strongly suspect that it would show that the RAM is just fine. (See why in the next bullet.)
- I have used the G5 Quad with 2.5 GB of RAM using all six possible combinations of 2×1 GB modules in addition to the 2×256 MB of RAM. In other words, I used the G5 Quad with modules 1 and 2, 3 and 4, 1 and 3, 2 and 3, 2 and 4, and 1 and 4. In all cases, I have ended up experiencing either a freeze or a kernel panic within more or less 48 hours, sometimes significantly less.
The only conclusion that I can reach after this is that there is a strong possibility that the 4×1 GB third-party RAM modules are not defective. After all, if the RAM was the culprit, to explain the situation described above, I would have to assume that three of the four 1 GB RAM modules have become defective at the same time—yet that the defects are not serious enough to show up during memtest’s battery of tests.
It is a rather unlikely explanation. Of course, the freezes do not occur with only the 2×256 MB of RAM (unless I have not waited long enough), so obviously the presence of the extra third-party RAM is a contributing factor. But that doesn’t prove conclusively that the third-party RAM itself is the problem.
Betalogue reader ssp was right to point out the problems that many people experienced with the late 2005 iBook G4 laptops. These people didn’t experience kernel panics or freezes, but there was a serious degradation in their laptop’s performance only when they had more than 1 GB of RAM in their machines. The problem turned out to be a bug in the AirPort software and was eventually fixed, but the important thing here is that it was a problem that only occurred above a certain threshold of RAM amount. So the RAM was a contributing factor without being the cause of the problem.
At this point, I am not quite sure what to do. Since I can connect the G5 Quad to my LAN via Ethernet instead of using the AirPort connection, I have tried turning AirPort off altogether on the G5 Quad, in case the problem has anything to do with AirPort. But I am not too optimistic… It’s been 24 hours and I wouldn’t be surprised if I get a freeze or a kernel panic in the next 48 hours or so.
If I do, then I guess the only option I will have is to get back on the phone with Apple and explain the situation. What I do know is that
- there is nothing wrong with the operating system or the software I use (since the G5 Quad runs fine, albeit slowly, with only 512 MB of RAM)
- there is nothing wrong with my USB and FireWire peripherals (since I got a freeze even with all peripherals disconnected except for my mouse and keyboard)
- the freezes and kernel panics only occur when I have some extra RAM installed
- there is nothing that proves conclusively that there is a problem with the third-party RAM.
I do not particularly fancy spending another $700 or so on more third-party RAM modules just to make sure that I would still get the freezes with another batch of third-party RAM. (I doubt very much that Apple would provide me with two “certified” RAM modules just to eliminate that possibility for sure.)
I don’t really see how I can contact the company that sold me the third-party RAM and tell them that it is defective and needs to be replaced. They are never going to believe that three or four modules have become defective at the same time. And I suspect that they might use memtest to test the RAM modules themselves and find that nothing appears to be wrong with them.
Unless switching off AirPort cures the problem and enables me to designate a faulty AirPort card as the culprit here, I am afraid the only other possible explanation is some other hardware defect in the G5 Quad itself. Maybe a defective RAM bus? I don’t know enough about the underlying technology. But I do know that there is a good chance that Apple will ask me to bring my G5 Quad to an authorized repair shop to have it tested.
The closest repair shop is a three-hour drive from here. And they are not going to be able to reproduce the problem easily. Like me, they are going to have to leave the machine on for several days, and try various combinations of RAM (possibly with their own “certified” RAM modules).
In all likelihood, this will be a lengthy process and I will be without my machine for an extended period of time. It’s still under warranty, of course (I bought the three year AppleCare warranty anyway), so the problem is not with the money. It is with the huge inconvenience of having to make several six-hour trips to the authorized repair shop and being without the machine for extended periods. (I’d have to go back to my G4 MDD, which I still use as a test machine, I guess. And of course I wouldn’t be able to use my 30″ display with it.)
This is all quite frustrating. And once again the back of my mind there are some rather serious question about the quality of Apple hardware in recent years… First, the unacceptably bad AirPort reception on the PowerBook G4. Then the horrendous noise issues with the G4 MDD. Then the traumatizing experience with the mooing MacBook. And now this?
Maybe I am just unlucky. Maybe my house is jinxed.
Or maybe Apple’s hardware is just not what it used to be.