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View Full Version : Sawtooth G4 randomly freezes




TheEdisonEffect
Mar 6, 2007, 11:04 AM
I'm trying to keep this old beast in service, and was planning on doing some upgrades to it, but I need to make sure this isn't a logic board problem first.

It randomly freezes solid. Cursor won't move, keyboard won't respond, any music that's playing will stutter in ~1 second loops... and there's no rhyme or reason to when it happens. Sometimes it'll freeze after 5 minutes, sometimes I can get days of uptime. It doesn't happen when using any particular program either. I've tried running all updates to 10.4.8, and I've also tried reinstalling with 10.3.9... makes no noticable difference. Watched carefully in Activity Monitor... nothing is obviously amiss. Also did the font cleanup, repaired permissions numerous times, pretty much any of the software maintenance I can think of.

Tried a different HD for my boot disk, thinking that could be failing... no luck. Tried reseating the processor card and replacing the thermal gunk... no luck. Tried completely different RAM... no luck.

I have to rely on this computer right now, but I can't trust it to do anything important, because of this issue. Help, please. Are there any obvious diagnostics I'm missing?

Edit: It occurs to me... is there some sort of log created upon a kernel panic? It doen't give me any error messages, but if there's an error log somewhere, that might help the diagnosis...



Sorkvild
Mar 6, 2007, 11:16 AM
I have a FW800 G4 and it used to freeze just like yours, with the audio looping constantly every second the moment it locked up. Took me about a year and a half to figure out that it would freeze when the CPU temperature reached somewhere around 50C. That's why it was so hard to reproduce and would occur at seemingly ranom times.

I had the processor replaced at an authorized Apple reseller and it was a little more than $300 :( , but it's fine now.

I hope I'm right, but you should make sure this is in fact the problem before you do anything.

TheEdisonEffect
Mar 7, 2007, 05:48 PM
I keep thinking it's the CPU, but it's not getting hot. I suppose it could be some other CPU problem beyond overheating, but between lapping the heatsink and replacing the thermal compound, the heatsink is cool to the touch even when the computer freezes...

I'm actually hoping it is the CPU, since that was one of the parts I was planning to upgrade anyway... but so far I haven't found a way to verify it without actually replacing the processor.

Any ideas how to check the processor? I know of plenty of PC programs that'll run such diagnostics, but none for Mac...

Lord Blackadder
Mar 7, 2007, 05:59 PM
By far the most common cause is heat...

If you're concerned that the processor is bad, I can't think of any diagnostics that you could run - but you could test it by stressing it. Run CineBench or demanding 3D games nonstop to see if the machine is less reliable under load.