PowerMac G4 Sawtooth CPU Upgrade

Discussion in 'PowerPC Macs' started by PowerHack, Apr 7, 2015.

  1. PowerHack macrumors newbie

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    #1
    Is it possible to swap the CPU in a 450 MHz sawtooth with a single 867 MHz from a (sadly fried) Quicksilver ?
     
  2. Arcady macrumors 6502

    Arcady

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    Lexington, KY
    #2
    I don't think it will run at the right speed, due to the 100mhz vs. 133mhz bus speeds. My guess is that it might work, but at 600mhz.
     
  3. bunnspecial macrumors 603

    bunnspecial

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    #3
    A QS card will need an extra +12V run to the 4th screw hole.

    I think the bus speed will also be a factor as mentioned-I've been meaning to test this for myself to see what happens.
     
  4. PowerHack thread starter macrumors newbie

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    #4
    Okay, I'm wanting to test it but unsure if I should. As I don't want to put my G3 (400MHz 576MB Rage 128) back into active duty.
     
  5. Ih8reno macrumors 65816

    Ih8reno

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    #5
    I tried putting a 733mhz Quicksilver card in my Digital Audio, doesn't boot at all and all I heard were fans.


     
  6. Intell macrumors P6

    Intell

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    #6
    It'll work, but you have to alter the Sawtooth's optical drive connector to make it fit and give the one post 12 volts. It will also not run at its full speed because of the bus difference.
     
  7. bunnspecial macrumors 603

    bunnspecial

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    #7
    I've actually been thinking this over for a week or two. My gut was that the processor would run slower due to the bus speed differences, but I've also known of examples Apple of processors changing their multiplier to run at their rated speed. Usually the multiplier is reduced(such as putting a 133mhz MDD processor on a 167mhz logic board), but thought that maybe a newer processor in a Sawtooth might actually run at its rated speed.

    In any case, I quite literally have a Digital Audio(133mhz FSB) sitting next to a Sawtooth(100mhz FSB). The DA has a 533mhz processor, which works out to a 4x multiplier.

    I stuck that card in the Sawtooth, and the Sawtooth reported it as 400mhz-or 100mhz x 4. See the below photos for pictures of the "operation" and the screenshot from the Sawtooth.

    I have an 800mhz Quicksilver processor lying in a drawer that I could have tried this in, but really didn't feel like soldering the 12V line onto it tonight(plus I intend for it to end up back in a Quicksilver, so don't want to mess up the mounting holes).

    So, based on that quick experiment, I'd say the above math is correct that an 867mhz Quicksilver processor will run at 600mhz in a Sawtooth.

    And, again, don't forget to run the extra +12V to it, or the computer won't work at all!
     

    Attached Files:

  8. PowerHack thread starter macrumors newbie

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    #8
    Okay, so it will run at 600 MHz. I'll probably install it just for fun, but to be sure, the fourth screw hole is the one which isn't being covered by the heatsink correct ?

    ----------

    Also, would it be possible to put a GeForce 4600 Ti (AGP 4x I believe) in the sawtooth despite the fact that it only has AGP 2x
     
  9. bunnspecial macrumors 603

    bunnspecial

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    #9
    Here's where the +12V goes on a Quicksilver card.

    A GEForce 4Ti will work, but the ADC out will not.
     

    Attached Files:

  10. PowerHack thread starter macrumors newbie

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    #10
    It Works ! Thanks everybody. Had to jam it into position as the IDE connector was in the way (as Intell stated) and it runs at 650 MHz ! All I did was grab some speaker wire, tape it (for the moment to test it) to the 4th hole, and then steal the 12v from an IDE power connector.
     
  11. Arcady macrumors 6502

    Arcady

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    #11
    650mhz makes sense. My previous math was flawed.

    867/133 = 6.5
    6.5 x 100 = 650mhz
     
  12. PowerHack thread starter macrumors newbie

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    #12
    Now its fully (partially) built. I soldered some speaker wire to the 4th hole, and connected it to the 12V fan that I installed on top of the CPU heatsink, removed the DVD Burner and the zip drive (as I don't use them and have a USB DVD burner), now the only issue is the top "tray" that holds the PSU.
     
  13. PowerHack thread starter macrumors newbie

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  14. flyrod macrumors 6502

    flyrod

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    Jan 12, 2015
    #14
    If you're set up for soldering, you could re-solder the jumpers that set the multiplier and get it running at full speed again. It would probably do 900MHz fine. Congrats on the upgrade!
     
  15. supernova777 macrumors member

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    Dec 22, 2007
    #15
    did u end up having to modify the ATA port to get it to fit?
     
  16. PowerHack thread starter macrumors newbie

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    #16
    Nope, I just cut off the top peice of the connector and basically jammed the CPU on. But its fully screwed in, the CPU board is *Slightly* warped (more curved than warped) but it runs.
     
  17. spf2 macrumors regular

    spf2

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    #17
    Congrats on the getting the CPU working. I would try and get the cpu board straightend out. Over time the warp can cause issues with the solder points on the board.
     
  18. PowerHack thread starter macrumors newbie

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    #18
    Thanks, I know. The current setup isn't permanent, eventually I'll just cut off/de-solder the ide connector but for the moment it runs.
     

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