RAM Pair is not recognized when placed together

[sabor]

Hi, my sister's PB G4 is experiencing some weird behavior I have not seen in the past. The machine used to be mine, and I had a 1 GB DIMM and 1 512 MB DIMM. She told me her computer was suddenly very slow and when I checked her system profiler memory info, it displayed ONE 512 MB DIMM.

I proceeded to do some testing and this is what I got:
------------------
Slot 1: 512 MB
Slot 2: 1 GB
Result: 1 GB shown is SP
------------------
Slot 1: 1 GB
Slot 2: 512 MB
Result: 512 shown is SP

At this point I thought Slot 1 was damaged, so I went with this config:

------------------
Slot 1: 512 MB
Slot 2: Nothing
Result: 512 shown in SP


What the hell is going on? The RAM seems to fine and the slots as well, it is the combination that is causing the lower slot not to recognize the RAM. I have resetted PRAM with no luck, reset permissions and so on.

Has anyone seen anything like this?

 

[mklos]

You must have a bad stick of RAM. Thats the only thing it could be. You can run the Apple Hardware Test CD and see if one of the sticks shows up as bad. It doesn't always detect bad RAM, but its worth a shot.

 

[Mpulsive81]

It would be tough to say, because it really does look as if it's a slot issue. It very well *could* be bad ram, but being that he inserted ram into slot 1 alone and it's working just fine, that kind of isolated the issue. Another way to test it would be to put the 1G in slot 1 & see what happens, that'll test the ram. Also run the same test on slot 2, just to make sure. That way, you're fully isolating the issue. I'm not familiar with the G4, so I don't know if matched pairs make a difference. I wish i could be more help. Good luck.

 

[mklos]

Another thing to do is if you have another notebook Mac or PC that takes the same kind of RAM that PowerBook has, put it in there and see what it does. See if it shows up correctly. See if the OS acts funny, crashes, or whatever.