Ram installation/slots for G5

Discussion in 'PowerPC Macs' started by redhatcode29, Nov 27, 2015.

  1. redhatcode29 macrumors 6502

    redhatcode29

    Joined:
    Jul 21, 2014
    Location:
    Kuala Lumpur
    #1
    hi guys.... can someone brief me of the ram installation for a G5 (Dual Core model, max is 16Gb ram)

    currently i have four sticks (2 x 512GB [green arrow] and 2 x 256GB [pink arrow]) installed. however the total rams read up to only 1GB. If i leave only two 512 s installed, the reading shows as 512Gb.

    (This pic is for illustration only)
    apple_power_mac_g5_motherboard_logic_board_630-7432_.png


    All rams read as 256gb as shown below.

    IMG_4157.JPG



    If i add more (tried 2x 512gb, 2x 1Gb, 2x 2Gb exactly paired), still, the total readings show as 1GB ram installed....worse, these extra fitted rams dont even show up in the memory slot in 'more info'.

    i also tried with only 2x 2gbs..... upon turning on, the warning sound was followed by a wild spin of the fans. why does it read as 256gb for all sticks ?

    i can brain it if the rams (512) are shown as 256 only....but the extra rams, that if i fit in more that the arrows shown..- that do not appear at a all....

    How do install more rams and overcome this issue of rams not even appearing in the info section. Thanks
     
  2. MacCubed macrumors 68000

    MacCubed

    Joined:
    Apr 26, 2014
    Location:
    Florida
    #2
    The RAM needs to be paired. Install one of the 512MB sticks in the bottom slot in the top section, and install the other 512MB in the top slot in the bottom section. Then install the 256MB sticks in the second bottom slot in the top section, and the second slot on the top in the lower section.
     
  3. redhatcode29 thread starter macrumors 6502

    redhatcode29

    Joined:
    Jul 21, 2014
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    Kuala Lumpur
    #3

    a mismatch ...ok, will try it out. thanks
     
  4. MacCubed macrumors 68000

    MacCubed

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    Apr 26, 2014
    Location:
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    #4
    No problem, hope my explanation wasn't too confusing lol
     
  5. bunnspecial macrumors 603

    bunnspecial

    Joined:
    May 3, 2014
    Location:
    Kentucky
    #5
    Swap the sticks around in ONE of the RAM banks and it should sort everything out.

    When I install RAM in G5s, I always start with the two innermost slots and build outward. This is an easy way to keep things matched.
     
  6. eyoungren macrumors P6

    eyoungren

    Joined:
    Aug 31, 2011
    Location:
    Phoenix • 85037
    #6
    I go in the opposite direction. I build out to in. But I also haven't had to match ram in a G5 very much either.

    Works out the same way though.
     
  7. MacCubed macrumors 68000

    MacCubed

    Joined:
    Apr 26, 2014
    Location:
    Florida
    #7
    I go in to out, it seems more organized that way. I put the lower capacity sticks on the slots further to the center
     
  8. Hack5190 macrumors 6502a

    Hack5190

    Joined:
    Oct 21, 2015
    Location:
    Stuck on Earth in the USA
    #8
    Doing some testing of memory modules I discovered that if you place (the correct type) of matched memory in the inner slots and mis-matched next the system will boot ignoring the mismatched (and any memory in slots beyond that). To me that means that the PPC reads memory from "in to out" (as MacCubed describes it).
     
  9. redhatcode29 thread starter macrumors 6502

    redhatcode29

    Joined:
    Jul 21, 2014
    Location:
    Kuala Lumpur
    #9
    nah...it wasn't. just had to read it twice. Thanks for your guide, i managed to place the rams in the correct position.

    However i have an issue where my 512 sticks read 256. i also tried a different set of 512, still the same, tried some swapping her and there ...only got worse, so left it at this current setting with 7GB though it suppose to be 7.5gb.

    i want to make it 8gb, it just won't let me do it!! thanks

    Picture 4 copy.png


    Picture 3.png
     
  10. redhatcode29 thread starter macrumors 6502

    redhatcode29

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    Jul 21, 2014
    Location:
    Kuala Lumpur
    #10
    i believe this is the same method as maccubed.
     
  11. redhatcode29 thread starter macrumors 6502

    redhatcode29

    Joined:
    Jul 21, 2014
    Location:
    Kuala Lumpur
    #11

    when i mismatch.....the the warning sounds, won't boot.
     
  12. Hack5190 macrumors 6502a

    Hack5190

    Joined:
    Oct 21, 2015
    Location:
    Stuck on Earth in the USA
    #12
    Here is the memory info from the G5 service manual

    [​IMG]
     

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