Upgrade iMac G3 via logic board swap?

Discussion in 'PowerPC Macs' started by Jiggly Billy, Jun 4, 2019.

  1. Jiggly Billy macrumors member

    Joined:
    Nov 2, 2012
    #1
    We may be picking up an iMac G3 400mhz DV model here soon, but I was wondering if you could swap in the later 500-700mhz model logic boards as a way to upgrade both the CPU & GPU at the same time. Would this work?

    Thank you all!
     
  2. philgxxd, Jun 5, 2019
    Last edited: Jun 5, 2019

    philgxxd macrumors regular

    philgxxd

    Joined:
    Feb 11, 2017
    Location:
    Malaga, Spain
    #2
    I tried a Summer 2000 500MHz motherboard from an iMac G3 Graphite and it were a simple swap for my 1999 400MHz iMac G3 DV. At least a 500MHz board from this moment in time will be possible to swap.

    I'm currently trying to repair a last model 700MHz and i noticed that the heatsink were different in shape and located slightly in another spot.

    I think you could move the older heatsink
    but a safer bet would be to have the divider panel of these newer iMacs. - I have to look again but i think the older heatsink is screwed while on the newer models it's fixed because it's part of the extruded metal divider panel-

    Here are some photos of the divider panel from the 700MHz model. I will try to add some of the other one ASAP.

    1. Upperside (where the CRT and PAV board sits)
    20190605_120854.jpg

    2. Underside (where the Logic board sits)
    There you have the heatsink with a thermalpad on it (i think it's 1mm thick)
    20190605_120944.jpg

    3. Close-up of the heatsink
    20190605_120959.jpg


     
  3. zackkmac macrumors 6502a

    Joined:
    Jul 7, 2008
    Location:
    Tulsa
    #3
    I have a graphite G3 400MHz (DV) and I swapped a 700MHz board into it several years ago from a snow model.

    In my case I don't recall there being any difficulties or the need to swap the divider/heatsink panel. In fact all I bought was the board itself.
     
  4. philgxxd macrumors regular

    philgxxd

    Joined:
    Feb 11, 2017
    Location:
    Malaga, Spain
    #4
    Interesting.
    Will have a look probably tomorrow and confirm if the heatsink is in another spot or not.
     
  5. philgxxd macrumors regular

    philgxxd

    Joined:
    Feb 11, 2017
    Location:
    Malaga, Spain
    #5
    1. Divider panel from iMac G3 500MHz Snow year 2000
    20190606_200632.jpg

    2. Divider panel from iMac G3 700MHz Snow
    year 2001
    20190605_120944.jpg

    There are quite different so be aware.
    Maybe it depends on where it was made also as there were made in US, europe and Asia.
     

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4 June 4, 2019