Build a PowerMac G5 - 1.8 CPU on 1.6 Board

Discussion in 'Macintosh Computers' started by Kyleniac, Oct 30, 2004.

  1. Kyleniac macrumors newbie

    Oct 30, 2004
    Hi Folks!
    I'm trying to gather PowerMac G5 parts on ebay to build one on my own.
    Will a 1.8Ghz G5 CPU work on a Logic Board from a 1.6GHz PowerMac?

    When I have the Logic Board, CPU, Case and Power Supply, GPU, RAM, HD, DVD-Drive, Fans - do I need anything else?

    Thanks in advance!
  2. Sayer macrumors 6502a


    Jan 4, 2002
    Austin, TX
    When a CPU unit is replaced in a G5 it must have a Apple tech-only software run that recalibrates the computer's cooling sub-system for the new CPU. Otherwise when you use the computer the cooling system won't know the default range and could run the fans at full blast or not fast enough.

    Also a mobo from a 1.6 GHz G5 may be somewhat restrictive compared to a 1.8 GHz (no PCI-X, slower/fewer RAM slots). There may even be different sockets (I'm not sure).

    If you manage to get all the pieces don't expect it all to "just work."
  3. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    They still have the same PCI-X controller all the other machines have, but since he's doing this he may want to look at the Hypertransport PCI-X bridge to find out who makes it and whether a resistor can be added/removed to enable PCI-X on the 1.6 machine.

    All they did was restrict the PCI-X bridge to PCI speeds, no biggie -- just the usual Apple feature crippling, like spanning on the iBooks.

    Though with some of the HT PCI-X bridges I looked at, this can be done with resistors -- also no biggie since Apple used the same board populated a bit different than the duals, what's a resistor of 2.

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