Overclocking iMac G4 800mhz

Discussion in 'PowerPC Macs' started by Doward, May 21, 2013.

  1. macrumors 6502a

    Joined:
    Feb 21, 2013
    #1
    Anyone know offhand which resistor bank controls PLL? iMac 17" 800Mhz G4. Looking to move it up to 900Mhz is all.

    Thanks!
     
  2. macrumors 603

    justperry

    #2
    Don't even bother, I overclocked my Pismo long time ago, from 500 to 550 MHz, unstable and does not make much of a difference.
    I said it before and say it again, if you want a faster Mac buy a faster Mac, overclocking does not give you much of a speed boost.
    Even a PATA/IDE SSD would do more than overclocking.
     
  3. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #3
  4. Doward, May 22, 2013
    Last edited: May 22, 2013

    thread starter macrumors 6502a

    Joined:
    Feb 21, 2013
    #4
    Much obliged, sir! Freebie system needs a little Leopard breathed into it. Now to dig through the old ram, see if I can make 1GB out of it ;)

    *edit*

    Very interesting. Cleaned the CPU, and I've got an XPC7451 800Mhz - not an XPC 7450 800Mhz. Wonder if 1Ghz might be in the cards ;) Also noticed I do have two points that the heatsink interfaces with the casing (dual heat pipes).

    I may go for 1Ghz, see if she's stable.
     
  5. macrumors 68000

    Joined:
    Jan 6, 2004
    Location:
    NH
    #5
     
  6. thread starter macrumors 6502a

    Joined:
    Feb 21, 2013
    #6
     
  7. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #7
    There's no substantial difference between 7450 and 7451. Only some bugs were fixed. Check this out if you're interested: http://www.freescale.com/files/32bit/doc/errata/MPC7450CE.pdf
    1 GHz is no go, I'm afraid, I've tried... 900 was stable on few, unstable on other ones (about 60/40).
    Motorola/Freescale has never clocked 7451 higher than 867 MHz. But there is a small headroom as usual.
     
  8. thread starter macrumors 6502a

    Joined:
    Feb 21, 2013
    #8
    Interesting. I thought the 7451 was part of the 'Apollo 6' family (ala 7455, etc) while the 7450 was Voyager?
     
  9. macrumors member

    MaxHeap

    Joined:
    Mar 28, 2012
    Location:
    Missouri
    #9
    On any G4 overclock, do you actually have to use the resistors or would jumping it with just solder work? Have a 867 MHz Quicksilver I may want to perform surgery on. :)
     
  10. macrumors 68040

    666sheep

    Joined:
    Dec 7, 2009
    Location:
    Poland
    #10
    Jumping with solder works well. Resistor isn't a must.
     
  11. thread starter macrumors 6502a

    Joined:
    Feb 21, 2013
    #11
    Correct, or you can use a thin strand wire and solder both sides of it down. :)
     
  12. macrumors newbie

    Joined:
    Feb 12, 2014
    #12
    Any luck overclocking your iMac G4? i have an 800mhz one that i was thinking about trying. I'm a little weary about bringing a soldering iron to it. i hear that going from 800 to 900 has only a 60/40 chance of being stable. Please post your results when you try it :)
     
  13. macrumors demi-god

    Hughmac

    Joined:
    Feb 4, 2012
    Location:
    Kent, UK
    #13
    Or, you can use conductive paint (such as is used to repair rear screen heater elements in cars).
    Use a pin and magnifying glass to apply it, and make sure it's dry before firing the Mac up.

    Cheers :)

    Hugh

    PS I must be one of the lucky ones, I've done a Pismo 400 to 450 and a Pismo 500 to 550 (both stable), using the above method.
     

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