View Full Version : Pwer Mac G5 onlys shows one processor

Nov 14, 2008, 05:15 AM
Hey all,

I have a Power Mac G5 Dual 2.7GHz which has been recently playing up. Sometimes it boots with both processors but lately it's booting with only one. What tests/diagnostics can I carry out to see what the problem is?

I *think* one of the processor may need to be reseated but I'm not sure I'm confident enough to try it and I don't want to pay Apple to do it just in case that's not the problem.

Any ideas?

Thanks in advance. :)

Nov 17, 2008, 04:53 PM
Is a long shot.. but who knows...

On a Power Mac you can disable a CPU in Open Firmware, so here's to hoping that after these Open Firmware commands you have enabled it by resetting:

1) (Re)Boot the Power Mac with the following keys pressed: <COMMAND> <OPTION> <O> <F>, until you get a grey screen with black letters.
2) Type the following:
reset-nvram <ENTER>
set-defaults <ENTER>
reset-all <ENTER>

After the last command your Mac should reboot, and hopefully both CPU's are working.

Good luck!