G4 won't accept new memory

Discussion in 'PowerPC Macs' started by ChrisC47, Sep 17, 2007.

  1. macrumors newbie

    Sep 22, 2006
    Atlanta, GA
    Hello all -

    I have inherited two PowerMac G4 450 MHz AGP machines for use at the non-profit arts organization that I help run. I believe these are either the "Sawtooth" configuration ( http://www.lowendmac.com/ppc/g4saw.shtml ) or the "Mystic" configuration ( http://www.lowendmac.com/ppc/g4mp.html ), probably the former.

    They each came with two 128 MB DIMMs (256 MB RAM each), which is anemic of course, so I bought two DIMMs of 512 MB RAM of the same type, intending to add one to each machine. Same bus speed (133 MHz) and voltage configuration (contact edge indents) as the existing memory. There are 4 DIMM slots.

    The DIMMs go into the slot just fine, but are not recognized by the system. It boots up as if they aren't there; there are no abnormal boot beeps or flashing power button. It just doesn't count them as existing in the RAM pool (per "About This Mac").

    I did try both DIMMs all by themselves, separately in the first slot and together in the first two, and those boots failed with the warning beep, flashing power button, and no video.

    I can take these back to the vendor (a trusted local whitebox shop) and have them test them, but is there something special that I need besides PC133 SDRAM?

    I noticed that these new 512MBs are 16-chip DIMMs, and the existing 128MBs are 8-chip DIMMs. Does that matter? I vaguely recall that there's a difference between 16-chip and 8-chip.

  2. macrumors 603


    Jul 17, 2004
    Macs generally tend to be pickier about their RAM than other computers. Did you buy generic PC RAM or did you buy "Mac Compatible" RAM?

    (Intel-based Macs don't seem to be as affected, but still like the good stuff)
  3. thread starter macrumors newbie

    Sep 22, 2006
    Atlanta, GA
    OK thanks Mechcozmo. I'll take it back to the vendor on Wednesday if I can't get it to work before then.

    Any other troubleshooting steps I can take? For example, is there anything I can do to make the machine run slower (i.e. be less demanding) just to establish that the RAM works in that mode? Or otherwise get the RAM working, albeit in degraded form?
  4. macrumors newbie

    Aug 25, 2007
    You can try different memory slots but that may not yield much.

    One thing you try to match is the CL (CAS Latency) number ----- look at your original DRAM they should either have a CL 2.5 or CL 3 best not to mix these. Also as mentioned above the Macs may have tighter timing tolerances ------ on my power pc G4 MDD I believe its spec'd for PC2100 DRAM (rated at 266MHz) --- when boosting it to 2GB (512 x 4) I chose to buy PC2700 (rated at 333MHz) ----- the price delta was like $3 more per stick. The Mac will automatically hold the bus speed at 266MHz and the "faster" PC2700 DRAM has a bit more timing margin
  5. macrumors 68040


    Dec 19, 2004
    The G4 AGP uses PC100 memory so you can get either PC100 or PC133. As others have said the Mac is just finicky sometimes.

    In the customer reviews various users have stated this memory works great in both G3 and G4 macs, and it is pretty cheap for such old memory $55.99.
  6. thread starter macrumors newbie

    Sep 22, 2006
    Atlanta, GA
    Thanks guys. I returned the memory to the local retailer yesterday, and will buy online today. Any other pointers to specific good brands would be appreciated, otherwise I'll just go with velocityg4's pointer to the Kingston RAM via NewEgg.

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