Did I just find some G5 plls?

Discussion in 'PowerPC Macs' started by rabidz7, Jul 15, 2013.

  1. rabidz7, Jul 15, 2013
    Last edited: Jul 17, 2013

    rabidz7 macrumors 65816

    rabidz7

    Joined:
    Jun 24, 2012
    Location:
    Ohio
    #1
    The resistors in the bottom right which are circled in black in the photo below are with 95% probability clock control jumpers for the G5. Will someone please try to jump one of them. The issue lies that I can not tell which PLLs are which.

    According to the IBM datasheet:

    BUS_CFG(0:2)

    The resistors that select core clock to bus clock ratio are:
    A11, D12, B11

    I am 95% sure that the three resistors are A11, D12, and B11, I do not now which is which, if you jump a resistor you are setting your processor to a completely unknown frequency.

    BUS_CFG(0:2)
    .....................Ratio
    ...............................Notes
    000................2:1

    001................3:1

    010................4:1..........1

    011................6:1..........1

    100................8:1..........2

    101................12:1........3

    110................24:1........2

    111................Not valid

    The MSB-PLL is the first objective, it has been completed. The FSB-PLL is the second objective, with the
    FSB-PLL overclocking would be possible without a new processor!

    I soon will take photos of my Quad 2.5 daughtercard and inspect the liquid cooling system for leaks.

    I cannot afford to buy another G5 with the 970FX and a CPU daughtercard, if someone could send pictures of your motherboard, and daughtercard, the one pictured is a 970MP, or if you are feeling very generous donate your G5?

    Sadly, none of that ratios (except the original) would work. 3:1, the lowest above the stock 2:1 would make the 2.3 970MP run at 3.45Ghz, which obviously is too high.

    A way to make it possible is to use a 2.5 970MP from a Quad or a 2.7 970FX (they should be the same, they are pin compatible so I don't think they changed anything in the daughtercard) in a motherboard with a slowest bus. For example, the 970FX in a PowerMac G5 Late 2005 dual 2.0Ghz. Those models use a 1Ghz FSB, so a 2.7 970FX card will run at 2.0Ghz. With the PLL modified to 001 (3:1 ratio) it should run at 3.0Ghz, which is a really slight overclock from 2.7.
    (Blue section originally posted by Andropov)
     

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  2. Giuly macrumors 68040

    Giuly

  3. Andropov, Jul 15, 2013
    Last edited: Jul 15, 2013

    Andropov macrumors regular

    Andropov

    Joined:
    May 3, 2012
    Location:
    Spain
    #3
    Do you have a higher resolution pic?

    And what is supposed to be the speed of that processor? If it's a 970FX and those are the PLLs, comparing 1.6, 1.8 and 2.0 should show the differences.

    PS: According to the data sheet, the 000 configuration means ratio 2:1 desoldering the third resistance (if it's the PLL) would boost it to 3:1.
     
  4. rabidz7 thread starter macrumors 65816

    rabidz7

    Joined:
    Jun 24, 2012
    Location:
    Ohio
    #5
    That one is a 970MP at 2.3GHz.
     
  5. rabidz7 thread starter macrumors 65816

    rabidz7

    Joined:
    Jun 24, 2012
    Location:
    Ohio
    #6
    BUS_CFG(0:2)
    Bus configuration
    Select core clock to bus clock ratio.
    A11, D12, B11

    ----------

    BUS_CFG(0:2)
    Ratio
    Notes
    000 2:1

    001 3:1

    010 4:1 1

    011 6:1 1

    100 8:1 2

    101 12:1 3

    110 24:1 2

    111 Not valid
     
  6. Andropov macrumors regular

    Andropov

    Joined:
    May 3, 2012
    Location:
    Spain
    #7
    Sadly, none of that ratios (except the original) would work. 3:1, the lowest above the stock 2:1 would make the 2.3 970MP run at 3.45Ghz, which obviously is too high.

    A way to make it possible IMHO is to use a 2.5 970MP from a Quad or a 2.7 970FX (they should be the same, they are pin compatible so I don't think they changed anything in the daughtercard) in a motherboard with a slowest bus. For example, the 970FX in a PowerMac G5 Late 2005 dual 2.0Ghz. Those models use a 1Ghz FSB, so a 2.7 970FX card will run at 2.0Ghz. With the PLL modified to 001 (3:1 ratio) it should run at 3.0Ghz, which is a really slight overclock from 2.7.

    The main problem is the VCore. Do all G5s use the same VCore? If not, we should find a way to change it or it will be unstable.


    However, I think it should be easier to overclock a G5 by overclocking the FSB instead of the processor. Because even if clocking the G5 at 3Ghz is posible, in order to do it using the PLL settings in the processor, using a lower clocked FSB is required, so the performance may not change. IMO, using the same ratio but with an overclocked FSB is the best option.
     
  7. rabidz7, Jul 15, 2013
    Last edited: Jul 17, 2013

    rabidz7 thread starter macrumors 65816

    rabidz7

    Joined:
    Jun 24, 2012
    Location:
    Ohio
    #8
    The MSB-PLL is the first objective, it has been completed. The FSB-PLL is the second objective. I cannot afford to buy another G5 with the 970FX and a CPU daughtercard, if someone could send pictures of your motherboard, and daughtercard, the one pictured is a 970MP, or if you are feeling very generous donate your G5?

    ¿Hablas español? Estas en España!
    El MSB-PLL era el objetivo primero, el FSB-PLL es el objetivo secundo. Yo no puedo comprar otro G5 con el 970FX y una tarjeta de procesador, si algún puede tomar photos de tu placea bace, y tu tarjeta con el 970FX, el que esta en la photo que puse aqi es un 970MP, o si tu sientes muy generoso dona tu G5.
     
  8. rabidz7 thread starter macrumors 65816

    rabidz7

    Joined:
    Jun 24, 2012
    Location:
    Ohio

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