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mishakim · Jul 11, 2008, 10:07 PM

My MDD dual-867 G4 has become unusably unstable. Aside from bad memory or bad HDD, is there anything else I should check before buying more? (i.e., what can I check before I waste $ if it's not the memory) I've already wiped the HD and restored from Time Machine with no improvement, can't reinstall from Leopard disc b/c it says installation medium is bad (it's not)

Here are the current symptoms: with 10.5.3, safari, mail, and firefox all crash after minimal use; frequent kernel panics; 10.5.4. update caused panic; can't mount 10.5.4 combo update image - bad checksum; sha1 value comes up DIFFERENT every time I check the update .dmg (multiple checks of same and different copies, having downloaded it on a working Powerbook - I think that's pretty conclusive for bad ram)

I have two DIMMs, tried removing each but problems happen with either: the original 256MB alone causes kernel panic moments after apple logo. The non-original, 5 y.o. 512MB alone allows boot but doesn't fix the stability;

Unless Leopard simply can't boot (and causes instant panic) with 256, this implies both DIMMs went bad at the same time (or all the crashes the bad one caused broke the good one).

Simon · Jul 12, 2008, 03:30 AM

Have you tried just running Apple Hardware Test and seeing if it reports any bad hardware?

idykenano · Jul 12, 2008, 09:59 AM

I don't think leopard runs well on 512mb of ram, I had issues running 10.5 on 1.25mhz emacs with 512mb, even an upgrade to 768mb helped.

imitchellg5 · Jul 12, 2008, 01:54 PM

It doesn't seem to be the RAM. The HD shouldn't be it either I'm guessing that it could be your graphics card. But run Hardware Test first.

mishakim · Jul 12, 2008, 09:02 PM

Originally Posted by imitchellg5

It doesn't seem to be the RAM. The HD shouldn't be it either I'm guessing that it could be your graphics card. But run Hardware Test first.

Unfortunately I can't find the disks that shipped with it to run Apple's hardware test. I do have the hardware tools disc that came with applecare on my powerbook, and that finds no problems.

Why do you say it's not the RAM? Would messing with the system RAM change the timing of when a GPU problem causes a panic? (during boot vs. after use)

mishakim · Jul 12, 2008, 09:07 PM

Originally Posted by idykenano

I don't think leopard runs well on 512mb of ram, I had issues running 10.5 on 1.25mhz emacs with 512mb, even an upgrade to 768mb helped.

I know it won't run well, but it should just be slow, not unstable, shouldn't it?

Simon · Jul 13, 2008, 01:49 AM

Originally Posted by mishakim

I know it won't run well, but it should just be slow, not unstable, shouldn't it?

I would say so as well. Leopard definitely needs 1GB at the very least. But I don't think it should be acting up that way just because you run it with 512 MB.

P · Jul 13, 2008, 12:15 PM

Originally Posted by mishakim

Unless Leopard simply can't boot (and causes instant panic) with 256, this implies both DIMMs went bad at the same time (or all the crashes the bad one caused broke the good one).

It's enough that one DIMM is flaky and damaged the OS during say an installation of an update - that would lead to something like this.

I can't tell you what it is, but if I had to bet, I'd buy 1 GB of RAM, remove both of the other sticks and Archive and Install. Newegg has 1 gig of SDRAM from about $30 (although I'd add a few bucks to get to Kingston or Corsair or similar - the cheapest models look flaky o me) and reinstalling is not that big a deal.

milhouse · Jul 13, 2008, 01:51 PM

You might also look at the ribbon cables for the HD as well as the power supply. A bad cable is a real pita because it's often overlooked.

If your PS is on it's way out, you'll get instability as well. It's not uncommon to see a bad PS.

I had tons of hangs (not so much crashes) when an internal HD (not my boot drive) started giving up the ghost on my MacPro. Unless you are seeing I/O errors, I doubt it's a drive.

mishakim · Jul 13, 2008, 04:50 PM

Turns out it was (at least) one bad DIMM. I downloaded memtest, and using it under single user mode with one DIMM at a time, the 256 had no errors and the 512 failed nearly every test. I picked up a couple of 512s cheap from MicroCenter and it seems that all is well. I was able to apply the 10.5.4 combo update, so I think I'll let it ride for a while before doing an archive install, though I may still need to do that if the bad ram corrupted anything in the time machine restore that the combo update didn't replace.