PowerMac G5 (late 05) reading ram speed wrong?

Discussion in 'PowerPC Macs' started by California, Oct 18, 2008.

  1. California macrumors 68040


    Aug 21, 2004
    Just put three more gigs of ram in Powermac Dual Core 2.0 late 2005 with bluetooth airport.

    Instead of reading the memory as PC2 4200, it is reading it as PC2-3200U-288 and PC2-3200U-266?

    And it still shows up as four gigs total (the correct amount) and says the ram is "OKAY".


    Am I hurting the Powermac?

    Am I getting full speed out of it?

    Canada Ram, I don't get it!
  2. OrangeSVTguy macrumors 601


    Sep 16, 2007
    Northeastern Ohio
    It automatically down clocks it to PC3200.

    Do you have PCI-X or PCIe?
  3. zmttoxics macrumors 65816


    May 20, 2008
    The ram is too new for the machine. The safe clock for unidentified ram is the slowest. Here is a screen shot of my G5. The 3200 sticks are actually PC2-6400. There shouldn't be any issues with this setup.

  4. zmttoxics macrumors 65816


    May 20, 2008
    Late 2005 = PCI-E. The machine takes up to 16GB of DDR2 with a correct clock speed of PC2-4200.
  5. zmttoxics macrumors 65816


    May 20, 2008
    LOL. I just realized I paired my RAM wrong. I will have to fix that later.
  6. California thread starter macrumors 68040


    Aug 21, 2004
    Well pulled the sticks and it was acting very very very slow. I think it is clocking down underspeed or something.

    Then I sold the PM on condition that it would respond better with Apple certified ram. We'll see.
  7. spirochete macrumors newbie

    Nov 11, 2003
    London England
    RAM speed checking.....

    Interesting issue......

    I too noticed that 2 x 1Gb Crucial 5300 'sticks' were reporting as 3200U-288 in my PM G5 Quad core 2.5 (late 05).

    To get a quantitative feel as to whether they were slowing the Mac down I ran 'G**kBench' on it (OS only, no other apps running), with:-

    a) Mixed Crucial and Apple RAM (reporting both 3200-288 & 4200-444)

    b) 2 x 1Gb crucial PC5300 sticks ONLY (reporting as 3200U-288 )

    c) 2 x 1 Gb original Apple RAM ONLY (reporting as 4200U-444)


    Hardly a scrap of difference!.......

    Setup with the Apple RAM only was very slightly slower (less than 0.1% difference) compared to mixed RAM

    Setup with Crucial (supposedly slower) RAM only - slightly faster (about 0.1%) than with Mixed RAM and therefore about 0.15% faster than the Apple RAM only configuration.

    Actual overall benchmarks were:-

    a) 1746 (mixed ram)
    b) 1743 (Apple 4200U-444 ram only)
    c) 1757 (Crucial PC5300 / [3200-288] ram only)

    So what does that tell me?

    Accepting that this may not be a definitive or the only test..... it would seem that whatever the Profiler is saying, the machine isn't adversely affected one way or the other with these mixed / mis-reported chips.

    What is a bit sobering is the Benchmark figure of 1750 compared to my Mac Pro 3.2 8core's score ....... which was around 13,000.

    Makes you think!

    Regards to all

  8. BugMagnet1 macrumors newbie

    Mar 4, 2012
    Apple service training material says:

    "The Power Mac G5 (Late 2005) uses PC2-4200 (DDR2-533) (or faster) memory. DDR2-400 [PC2-3200] memory will prevent the computer from booting correctly."

    It lists PC2-4200, 5300 and 6400 as acceptable.

    On my system, both PC2-5300 and PC2-6400, while working, are registered as "3200U-288".

    Even though it sees the faster memory as 3200, is still boots correctly. Could it be that it is actually running faster then than the scan info implies?

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