I got memory problems and I don't mean amnesia!

in Genius Bar edited January 2014
Ok, I've replaced and upgraded PC and Mac memory without trouble before but somethin ain't right this time around.

Here's the deal: I have an iMac G4 800mhz 17" and I wanted to up the RAM now that I have Tiger. I went out and bought (or at least asked for) a 512mb PC133 SO DIMM. The guy kept calling it laptop memory but it was the exact same shape and size as the 256mb card currently in there so I figured it was what I needed. Is that where I went wrong? I installed it without trouble BUT it just doesn't register. In System Profiler it says the DIMM0/J22 slot is empty, empty, empty. I reseated it a few times but same deal.

So that's my problem...but here's SOMETHING ELSE STRANGE that may or may not be related. Notice how I said the current card is 256? Well, I only just now realized that it's registering as 128. Sys Profiler says:

DIMM0/J22 128mb SDRAM PC133U-322

DIMM1/J20 256mb SDRAM PC133U-333

So I have 384mb of RAM with two 256mb chips?! Is this some special math or is something wrong?

Geniuses...please enlighten me!


  • Reply 1 of 4
    joblowskijoblowski Posts: 32member
    Wow, seriously nobody knows what's going on when two 256mb ram chips add up to 384mb? Any guesses?

    C'mon, help a brother out!
  • Reply 2 of 4
    godriflegodrifle Posts: 267member
    I'd look for a ram mismatch. This tends to happen if you use double sided RAM in a machine that requires single sided. I'd contact the guys at 4allmemory.com, as they are really up on RAM requirements for Apple products.
  • Reply 3 of 4
    joblowskijoblowski Posts: 32member
    Thanks for the reply godrifle. I talked to a Mac specialist and also the place where I bought the RAM and they both tell me Macs don't much care about single vs. double-sided.

    So the user-servicable slot must be bad since I have a 256mb chip that shows as 128 and a 512 that doesn't show at all. Damn, that sounds like it'll be a pain to get fixed and I'm sure will cost more than the new RAM did to begin with!

    Guess I'll stick with my 384mb of RAM...that's not too bad, I guess.
  • Reply 4 of 4
    godriflegodrifle Posts: 267member
    If these guys call themselves Mac experts, and they make that claim, I would run away as fast as you can. It's widely known that Apple computers have very stringent memory requirements, specifically double vs. single sided, the power differential between the two, and timing issues. Sure, it could be bad RAM, or a bad memory controller on the mobo, but it sure sounds suspiciously like a memory mismatch.Try contacting the guys at www.ramjet.com. They're real helpful too.
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