[El Maestro]

Hi All,

I've got a PB G4 17" 1.67 (Rev. D) running 10.4.3. I have the 512 MB RAM chip that came with the machine.

Over the summer, I added a 1 GB chip (Samsung) I bought from OWC. All was great!

Tonight, I was using a few apps-Safari, Adium-and I got a Kernel Panic. When I rebooted, I went into "About This Mac", it said that I only have 1 GB installed with two 512 chips. The slot that has the 1 GB chip is the "Reversed" slot, and it showed up as only 512, status and everything were listed as OK. I am not using any attached peripherals at all. Logging out and restarting did not solve the problem.

I reseated and reversed the chips, and the same problem happened: the 1 GB chip showed as 512. I then put everything back as it was and ran Disk Utility from the installation disks that came with the machine and repaired permissions and the start-up volume. I rebooted, and lo and behold, I had 1.5 GB RAM again! I ran Apple Hardware Test (extended), just to be sure, and everything passed.

I rebooted again and was using the computer normally (with correct RAM), and then as I was launching an App, I got a Kernel Panic. After the restart, I am missing RAM. Everything functions just fine, I'm just short some RAM!

So, is there anything else I can do to either stop this, or failing that, determine if it's the stick or the slot? I have AppleCare, so I'm not too worried.

Thanks for any help!

UPDATE:

I restarted again and I've got the 1.5 GB. Though, there were two more Kernel Panics. The disappearing RAM issue seems to have abated, though. This seems to be happening when Safari is open. This can't have anything to do with the Java Update from a few days ago, can it?

[tigas]

No, it seems very likely that it really is RAM problems. Try to run the Apple Hardware Test CD for your machine, it usually flags memory problems. It nailed a problem I had with a 512MB stick a friend had lent me and that was also causing kernel panics. "Error 3 in RAM module JP0" IIRC.

[El Maestro]

Thanks for the reply.

What's happened since this started is that the 1GB chip either registers as 512 or is not detected at all. I experimented with various configurations of each chip in either slot and some interesting things happened:

With the 512 chip that came with the machine, all works fine when it is by itself in either the standard or reversed slot.

The 1 GB chip shows up as 512 in the standard slot. In the reversed slot, it shows up as 512, but there is no start-up chime, though it boots normally otherwise (minus the correct RAM). Randomly, the 1 GB chip won't be detected at all, in either slot. I think what I'll do next is try it without the orginal 512 chip in the other slot.

In every case, both chips always pass both the Apple Hardware Test and memtest. What I think is happening (I could be totally making this up), is that the Mac is ignoring the bad part of the 1 GB chip, since it passes all tests and there are no Kernel Panics when it registers as 512. I know the Mac OS is smart, but is it THAT smart?