I have a friend's iMac 233Mhz that I would like to upgrade with more memory. I believe it's the Rev A model. The thing is, I already tried a 128MB sodimm in it and it failed the system's RAM check when you first turn it on. I've tried using the same sodimm in other imacs before and it would never work but, curiously, it would work on PC laptops (which is where it was pulled from). So my question is are iMacs picky about their RAM? Are there any brands that are known to work well consistently? I want to buy it used but I'm afraid it won't be compatible. I can probably try it out before I buy but I don't want to keep having to open the iMac each time the memory isn't working (it's the model where you have to pull out the entire brains and remove the shield over the memory).