[Q27]

I recently purchased an iBook 900MHz with the 128MB built in, I thought I would upgrade it with some crucial ram. I installed a 256MB chip, but when I checked "About this mac", it still says only 128MB. The ram is PC133 CL2 from Crucial. But now that I look it says to use PC100 according to the manual. I read something a while back on how PC133 wasn't going to be compatible with PC100 slots.

[I Me Mine]

I use PC133 in my 800mhz iBook and it works fine.

Maybe the memory module is faulty? Can you try it elsewhere perhaps?

Or get in touch with Crucial.

[SupahCoolX]

PC133 is fine in a 100 slot (it just won't reach its full 133mhz speed potential).
Check that the RAM is seated properly, too. It should fit all the way into the slot, and the clips on either side of the chip should latch on.

[radarbob]

I ran into this problem when I purchased our 700MHz iBook. The memory was dealer installed. Taking it back for a swapout, the techie explained that the Mac is programmed to recognize specific RAM modules. Thus, some won't be recognized even if they are otherwise pin for pin and electrically compatable.

[-Q-]

Originally posted by radarbob:
I ran into this problem when I purchased our 700MHz iBook. The memory was dealer installed. Taking it back for a swapout, the techie explained that the Mac is programmed to recognize specific RAM modules. Thus, some won't be recognized even if they are otherwise pin for pin and electrically compatable.

That sounds like a load of BS to me. Apple has instituted some memory checks that make it less tolerant of poorer-quality memory modules, but the idea that it's programmed to only use specific modules is ludicrous. I use some no-name 512 chip in my 800 just fine.

My hunch is that the module is either seated incorrectly or that it's bad. Double check the installation and if it's firmly in place (and follow the instructions under the keyboard exactly--that method works best for ensuring it's installed correctly) then you may have a bad RAM chip.

[finboy]

Originally posted by -Q-:
That sounds like a load of BS to me. Apple has instituted some memory checks that make it less tolerant of poorer-quality memory modules, but the idea that it's programmed to only use specific modules is ludicrous. I use some no-name 512 chip in my 800 just fine.

My hunch is that the module is either seated incorrectly or that it's bad. Double check the installation and if it's firmly in place (and follow the instructions under the keyboard exactly--that method works best for ensuring it's installed correctly) then you may have a bad RAM chip.

There used to be a utility called DIMMfix that would take care of resetting the CL on the RAM. I don't know if that would apply here or not.