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View Full Version : Powermac G4 CPU upgrade kernel panic and freezing.




tipman2000
Jul 1, 2010, 01:30 PM
i have a sawtooth G4 that came with a 450MHz chip, but is getting a bit slow. i didnt feel like spending $300 on a CPU upgrade and i am somewhat of a novice modder so i decided to go pick up a DP G4 500 on craigslist. this one has a fried PSU, and i know i could just stick the psu from the 450 in there but instead i decided to fit the dual 500 into the single 450 case, since all my stuff is already in there. the first time i tried to boot with the new cpu installed, it gave me a bong then lost power before giving signal to the display. i booted it again with the new DP 500 but the same thing happened, so i figured maybe i needed new thermal paste since i took the heatsink off of the cpus during the switch, and this helped me get to the apple logo during the boot process, but then a sort of black curtain rolls over the logo and the whole computer loses power. after a few more tries, i somehow get it to fully boot! i know this is a problem with the cpu, because upon putting the old 450 back in, it works fine... but anyway, after finally managing to boot the dual 500 after numerous kernel panics, i *attempted* to open activity moniter, and then the whole thing completely freezes. after a few more tries and a reset to the pram, i boot it again, and it works fine, that is until i try to do anything taking a lot of cpu cycles, like playing a youtube video that froze it again. hmm, beginning to see a pattern here? it seems when the cpu gets stressed, it freezes... im thinking that somehow the cpu is not getting enough voltage? but im not sure so im asking you guys if you can help? thanks.



666sheep
Jul 1, 2010, 02:56 PM
First, check is your Sawtooth supports DP dcards (not every do). Use this small utility: http://www.macupdate.com/info.php/id/13551/uninorthasicchecker
If it'll pass this test, do all possible resets: PRAM, nvram, PMU (formerly named CUDA).
You can also check is heatsink is properly touching CPU cores and check your fans too. Freezes are mostly heat related, but KPs are not. Maybe there's not only one issue?

Your "donor" is Gigabit Ethernet (with DP known as Mystic). PSUs are not quite identical, there is small difference in pinouts and logic board connector length: http://www.outofspec.com/frankenmac/wire.shtml When you put Sawtooh PSU into GE, you'll lost ADC power line, but OFC if you don't want to use ADC output, it should no matter.
GE has one advantage over Sawtooth: Gigabit Ethernet port (Sawtooth has 10/100 ethernet). If it's important to you, and you do not plan to use ADC card, you can simply swap PSUs between computers and move all your stuff to GE.
Keep us posted, it's always nice to know about another one "resurrected" old Mac :)

tipman2000
Apr 4, 2011, 03:51 AM
sorry it took a year to reply, unfortunately the proect was scrapped after the dual 500 card was found to be dead, so i put the single 450 back in. then the old hard drive failed, so i got another. then the psu stopped working, so i gave it up. i got to smash the hard drive with a sledgehammer, that was fun.:D:D