G5 dual 1.8G PPC will not recognize more than 512mb slots 6 & 7

Discussion in 'Mac Desktops' started by rob@ntpap3r$, Mar 12, 2018.

  1. rob@ntpap3r$

    rob@ntpap3r$ New Member

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    This is a weird one...

    When I install 1Gb DIMMs in slots 6 & 7 the machine reports that they are 512 Dimms whereas all the others are working fine. If I install 512Mb sticks it sees them as what they are. I am thus stuck at 7Gb total ram. These are all Samsung PC3200U 30330s with the exception of the two 512Mb sticks which are Hynix PC3200U 30330s...

    This also occurs when I install some Corsair 1G sticks as well...

    I realize this is an older machine but they still perform very well in our application which is typesetting newspapers and magazines and I would like to sort this out although it works fine with the 512Mb sticks in and a total of 7Gb...

    I've tried the command-option-R-P on boot up to no avail...

    Many thanks in advance for any ideas;)

    Rob
     
    rob@ntpap3r$, Mar 12, 2018
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  2. rob@ntpap3r$

    honestone New Member

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    From what I understand, there are, typically, three things about this:

    1. The design of the machine itself.
    2. The Mac OS one is using.
    3. How much Ram applications can address.

    From what I can tell, this is your Mac:

    https://everymac.com/systems/apple/powermac_g5/specs/powermac_g5_1.8_dp.html

    So, the maximum amount of Ram that can be installed is 32 Gig (4 gig in each of the 8 Ram slots). Also, according to that link, the maximum non-OS 9 OS that you can use is OS 10.5.8.

    Here are the results of a google search of "Maximum Ram recognized by OS 10.5.8":

    https://www.google.com/search?q=Max...ome..69i57.12917j0j4&sourceid=chrome&ie=UTF-8
     
    honestone, Mar 12, 2018
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  3. rob@ntpap3r$

    rob@ntpap3r$ New Member

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    Thanks for that honestone...

    yep... it's the model you stated and running OS X 10.5.8. It's weird because it used to be fine and then one day threw a wobbly during a save. I lost the file entirely (it was an Indesign project that had become corrupted by whatever happened and subsequently trashed) and my first thought was a Ram failure. I tried reseating it and then swapped the modules around a bit and it reported 8Gb for a short time but reverted back to 7Gb. I put the Hynix 512Mb modules in and used the 1G Corsair modules in another machine where they work fine. I've since got a load of Samsung modules in and thought I'd throw them in my machine to see if they worked but got the same result - slots 6 and 7 only recognizing half the RAM per stick...

    Like I say - it's not like there is a significant difference in performance between having 7 or 8 gigs of RAM... and I limit how many apps are open at any given time... especially Photoshop... and have to boot a OS X 10.3.5 startup disk now and again to use an old version of Quark (which ties into an even more ancient handful of Prostations running 9.2!) so it gets re-booted a couple times a day. It sees the two 512M sticks OK so... que sera sera...

    I just wondered if I was missing something...

    Many thanks again!!
     
    rob@ntpap3r$, Mar 12, 2018
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  4. rob@ntpap3r$

    honestone New Member

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    You're welcome. Wish I could be of more help.
     
    honestone, Mar 12, 2018
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  5. rob@ntpap3r$

    Cory Cooper Moderator

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    Hello and welcome.

    Are you installing the DIMM pairs properly - in pairs from the two center slots out:

    [​IMG]

    If not, they won't be installed properly, take advantage of memory interleaving, and show correctly in About This Mac/System Info.

    Also, as noted in the manual:

    DIMMs must be installed in equal-sized pairs and fit these specifications:
    • 400 MHz, PC 3200 DIMMs
    • 2.5 volt (V)
    • 184-pin module
    • Maximum number of memory devices on DDR SDRAM: 16
    • Nonparity
    • No error-correcting codes (NECC)
    • Unbuffered(registered or buffered DDR SDRAM cannot be used)

    C
     
    Cory Cooper, Mar 12, 2018
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  6. rob@ntpap3r$

    rob@ntpap3r$ New Member

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    Hi Cory,

    Many thanks for taking the time to publish that graphic. They are all Samsung M368L2923DUN-CCC and are therefore, according to the Samsung datasheet, fully compliant with the above requirements...

    I'm going to just accept that this particular unit will only accept 7Gb for whatever reason and back it up regularly... all of our work is stored in a couple of 4Tb servers and we only run four of these old G5s all on OS X 10.5.8 with the one exception being this particular machine which has an extra HDD which has 10.3.5 on it so I can flow legals and classified via the Classflow extension in Quark 6. That is necessitated by some even more ancient Ad Manager software running on a couple of old Prostations that run 9.2 and those are necessitated by the fact that AM software will not run on OS X and the files it produces are used by Quark and Adforce on our G5s and an old AS400!! We even have a foolscap width dot matrix printer to go with the AS400 :p

    Thanks again to yourself and honestone for taking the time to reply... I'm going to tuck my tail in on this one and hope for the best!!
     
    rob@ntpap3r$, Mar 13, 2018
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  7. rob@ntpap3r$

    Cory Cooper Moderator

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    No worries.

    I totally get your position with the older hardware. I did some work with prepress and printing companies back in the day, so I know how important it is to not upset the workflow.

    It could be that the slots are just aging, and therefore aren't working properly. That G5 should report the full 8 GB. I would definitely keep an eye on things, and if you continue to have corruption, be ready to eliminate slots 5-8 totally to see if that fixes it.

    Keep us in the loop and good luck.

    C
     
    Cory Cooper, Mar 13, 2018
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