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

  1. #1
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    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
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    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
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    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
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    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
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    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
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    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,

  7. #7
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    Hm. I was in the middle of making a post here a couple hours ago, when it crahsed for the second time today. But its a strange crash, the mouse laser goes dark, but the bluetooth adapter still blinks as if its getting power. The system is crashed through because the clock stops.

    Strange.

    I archived and clean reinstalled Tiger just now, but it crahsed again in the same way when starting up for the first time in this fresh system.

    The thing is, its done this a time or two years ago where the system crashes and the mouse laser shuts off, and that was before I ever even openned the case really.

    Its a strange problem, because it was working just fine for a couple nights, yet it seems to be crashing every now and then today. Oh well. Ill have to wait and see more about when it likes to do it and how often before I open anything up again. If it continues to do it i think ill up the core voltage .05v and see if that helps.

    Thanks for all of the replies

  8. #8
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    The button you are refering to is called a PMU (Power Management Unit), and while it can be a big help when changing hardware and troubleshooting a sick Mac, by resetting things back to the factory defaults, I really doubt it would make any difference regarding issues that arise when you over clock.

    I can't help with voltages. I would expect that at a certain point you can kill the CPU, so go slow. If it were me I clock the CPU back down a bit, and be happy to have a stable machine at about 1 ghz without having to buy a CPU. But that's me.

    On my BW G3 (sold it a while back), I was able to overclock the G4 upgrade CPU from 500 to 550 by doubling the heatsink area to handle the extra heat, and still have it rock solid for months at a time. Does not sound like much, but the old 7400s were about maxed out as it was, and many could not be OC'd at all or would be unstable. Newer G4s starting with the 7410 seem to be clocked more conservatively....but it sure seems like much more than 10% is starting to push it; and you are around to 20%, so don't be surprised if the answer ends up being to clock it back down a bit.
    "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

  9. #9
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    Default

    It seems to be running fine at 1Ghz after its been warmed up and has crashed a couple times


    Ill have to see if it will continue to crash often with this setup. if it crashes more than once a couple weeks I will up the voltage again just by .05v and see what that does, the only reason why its running as well as it is now is due to a .1v increase.


    Another factor is that the way its crashing is the same that is did a couple times like 4 years ago, when I hadnt even openned the case yet. Its almost like a USB problem that happens to also hang the system.



    Its an old computer, but Id like to hang on to it until I can get a decent paying job and buy i guess what has now become Mactel Macs haha.


    Thanks for the replies! Ill keep it at what its at now and be happy. If theres something new Ill post it.


    nice forum by the way

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