International Mac Podcast

Hi all, it’s me, Matt Rhinesmith, back with another post, after a “short” delay. This time, I’m posting a little tidbit I found about overclocking ANY sub-533 MHz G3 or G4 Mac to 533 MHz. I have tried this personally on both my iBook and iMac G3, and I’ve definitely noticed improved performance. For example, as I write this post in Safari 4.1.1 with 3 tabs open, I also have Mail and Twitterrific open, and DVD Player open, paused.

While it definitely helps that I have the maximum of 567 MB of RAM installed, it would choke long before this at 366 MHz. These instructions are courtesy of Mark Sokolovsky, a netizen of LEM’s G3-5 List. You will want to print these out, since they’re not easy commands to remember. Also, where it says ” <something>, there is a space in between ” and <something>. That tripped me up when I first tried this. Anyway, here they are, exactly as he posted them to the list:

(1) Boot by holding down “Cmd” + “Opt” + “O” + “F” keys to enter the OpenFirmware terminal.

(2) Enter the NVRAMRC editor. (<return> shows you should type “return” key)
nvedit <return>

(3) Type following script exactly (including spaces).

” /” select-dev <return>
7efdc44 ” clock-frequency” get-my-property 2drop ! <return>
” /cpus/PowerPC,G4@0″ select-dev <return>
1fca0554 ” clock-frequency” get-my-property 2drop ! <return>
7efdc44 ” bus-frequency” get-my-property 2drop ! <return>
1fbf711 ” timebase-frequency” get-my-property 2drop !

(4) Type “Ctrl” + “C” to exit NVRAMRC editor.

(5) Save the script
nvstore <return>

(6) To enable the NVRAMRC, type this command.
setenv use-nvramrc? true <return>

(7) Reboot with new timebase constant.
reset-all <return>

Use this command to successfully overclock any G-powered PowerPC processor to 533Mhz without soldering. This only works on sub-533Mhz processors. As for PowerPC G3, use PowerPC,750@0 instead of PowerPC,G4@0.

Good luck, and I hope this works for you!

–Matt