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Thread: Max clock speed for 866mhz G4 power mac?

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  1. #1
    Join Date
    Feb 2006
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    35

    Default Max clock speed for 866mhz G4 power mac?

    Hi.

    Im quite new to this place, but I was looking for some info on overclocking macs and came across this forum.

    I have a G4 powermac, quicksilver i think 866 Mhz, 256L2, 2MB L3 caches, and I was having trouble pushing the speed over 1 Ghz due to what I think is L3 cache non activation or mis-performing.

    The max speed i think i can set the registers to is 1066 Mhz, but when I do that the computer lacks a startup sound, and the About This Mac screen says no L3 cache, and then it will crash soon and say You Must Restart.. yadda yadda..


    I had the same problem overclocking to 1 Ghz without boosting the core voltage .1 volt. It would run for a bit maybe with L3 cache, maybe not. But even with boosting the core voltage to (i think) the max of 2.1 the computer will not run stable at 1066 Mhz. The L3 cache wont come back.


    Currently its at 1 Ghz with a core voltage of 2.0 volts. (Originally 866Mhz and 1.9 volts(i think)) and seems to work ok at the moment.



    I am curious if 1 Ghz is the max i can run this computer or if theres something else i have to do to make it run stably at 1066 Mhz (1.07 Ghz)



    Thanks

  2. #2
    Join Date
    Jan 2002
    Location
    NW Montana
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    8,197

    Default

    Currently its at 1 Ghz with a core voltage of 2.0 volts. (Originally 866Mhz and 1.9 volts(i think)) and seems to work ok at the moment.
    I'd be as happy heck it's another 15-20+ percent. Nice job. The fastest stock QS was a Dual Gig I believe but people do put far bigger 3rd party processors in.

    Most out here leave the stock processors alone and if we are tweaking up it is usually a 3rd party product like a Giga. and they specify how.

    But others do like to tinker/tweak as you are.. they should stop by. - Randy

  3. #3
    Join Date
    Feb 2006
    Posts
    35

    Default Thanks

    Thanks.

    Im happy with 1 Ghz. It gives me that "out of the darkness" feel but just a little bit.


    1Ghz will be very decent if that is the max without upping other things like the bus which probably wont work anyways.


    But,,, hehe like i said if anyone knows anything simple to do in order to bump this up to 1.07 Ghz stably it would be very welcome over here Certainly, no other registers would be smaller or more teduious to work with than the original ones on this processor card.


    The temp as of now is 114.8 F. It hasnt gone higher than that no matter the Cpu load.? it just stays there or at 113 F. The fans arent going into faster mode or anything like that. Its about 73 F in the room here now. I figured that just the temp would be a problem with going faster than 1 Ghz, but apparently other things such as the L3 cache dont like it going that fast.


    Thanks again

  4. #4
    Join Date
    Feb 2001
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    on the landline, Mr. Smith
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    Default

    I would agree that to get to 1G is quite a good speed bump, all things considered. Let temps and stability be your guide; if a CPU is too hot, it may run well for a while, but you could cut its life short.

    You are on the right track about L3 too. Part of the reason that the latest 7447 CPUs lack L3 is that the Freescale (Motorola) could not get the L3 to clock high enough....so they chose to crank up CPU clock and leave out the L3.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  5. #5
    Join Date
    Feb 2006
    Posts
    35

    Default Hmm

    Hmm, I see.

    Sounds funny, but I wish i could just think about having something work and have it really work


    I have a question though. Im new to the forums, and in reading around a couple posts ive noticed someone was talking about a Mobo or Hardware Reset button somewhere on the Quicksilver board?


    I never pressed that, I didnt even take the plug or wires out of the back when I took the processor card out. All i unplugged was the headphone jack because the cord wouldnt reach far enough when the box was open.

    Do you think that it will work at 1.07 Ghz if I set it to run at that speed again, but this time press this Mobo reset button?


    Ive heard of a button like this before when upping my old, old beige power mac, but it was called a CUDA switch or something.


    Or, is no button going to make everything including the L3 cache work ok at 1.07 Ghz?



    Thanks Uncle !

  6. #6
    Join Date
    Mar 2001
    Location
    Virginia... where one Democrat CAN make a difference
    Posts
    2,929

    Default

    every processor I have ever overclocked was always held back by the cache failing at higher speeds

    My latest one is a 400/200mhz G4 zif that runs just fine at 500mhz but the cache crashes at anything above 220mhz
    Damien,

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