Black Flag Processor Swap

Discussion in 'Mac Pro' started by pc2macguy, Dec 5, 2008.

  1. pc2macguy macrumors newbie

    Dec 5, 2008
    I recently picked up an orphaned G4 tower with this set of specs:

    The Apple Power Macintosh G4/450 (AGP Graphics), based on the Sawtooth architecture, features a 450 MHz PowerPC 7400 (G4) processor with the AltiVec "Velocity Engine" vector processing unit and 1 MB of backside cache. It shipped configured with either 128 MB or 256 MB of RAM, a 20 GB or 27 GB Ultra ATA/66 hard drive, a 5X DVD-ROM or DVD-RAM drive, and either a 2X AGP ATI Rage 128 or Rage 128 Pro graphics card with 16 MB of SDRAM. AirPort (802.11b) was available by custom configuration.

    My question is this: The daughterboard plugs into the mainboard, but is the socket compatible with the 64-bit PowerPC 970 (G5) daughterboard?

    I do know that the frontside bus is set at 100mHz, based on the PC100 SDRAM that's in it, so I'd expect a slow G5 processor speed I HOPE.

    WHY would I attempt such an insane operation? To get Final Cut Pro to run on the box for school projects, nothing really long term.

    If it's an absolute NO-GO, would this machine be a usable web server if I topped off the board with the max 2gb RAM the processor allows, and upgrade the HDD?

    Trying to make SOMETHING out of what currently is borderline "nothing"...
  2. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    No, not at all ... the G5 uses a variant of the Big Iron FSB.

    Rather complicated and requires something akin to a G3 to sort out the handshaking between the CPU and the Northbridge and just bring it to a stable clock.


    Basically if you look at the FSB of the G4 as a 2-stroke lawnmower engine, the G5 would look as complicated as a 757 engine if all you know is lawnmower mechanics.

    It is tough and one company really was the only one that figured it out besides Apple and IBM -- the rest cried uncle and dumped the effort instead of call in IBM to teach them for 100k a week.

    Even the company that figured it out gave people the process to bring it to a stable clock and guessed that a room full of really smart people might take 90-days to figure out how to turn the CPU on, something that would take a day for the G4.
  3. TrapOx macrumors 6502

    Dec 4, 2008
    Its physically impossible to replace a G4 with a G5.

    It would be slow, but usable. If you are handy with a soldering iron you can bump up the CPU to 500mhz without a problem.
  4. SmurfBoxMasta macrumors 65816


    Nov 24, 2005
    I'm only really here at night.

    Please translate into english :)
  5. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    They put a bunch of really smart people into a room with a PowerPC970, it took them 6 months to figure out how to bring it to a stable clock -- aka, boot the CPU.

    Something it takes about a day with for an G3 or G4.

    Every time they changed something it took them another 2 weeks to recalibrate the G5 -- and bring it back to stable clock.

    Basically 1 company figured out how to make a motherboard without IBMs help.

    So, no dice on an upgrade -- since it was too expensive for anyone to pay IBM to teach them how to design boards.

    Lots of companies signed up to develop systems with the G5, really populated with smart people, and only 1 survived -- and they don't sell G5 boards anymore. Leaving the rest to simpy buy IBM boards.


    The G5 uses a really complicated FSB and boot to stable clock scheme.
  6. pc2macguy thread starter macrumors newbie

    Dec 5, 2008
    Thanks for the info...

    I appreciate the help...maybe I'll run it as a server since the Mac OS's are less hackable
  7. CarlsonCustoms macrumors 6502

    Mar 5, 2007

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