[frankmcma]

I have a G5 dual core, it started shutting down for no reason periodically. Just total no-warning pull the plug shut down.

Fans seem to be working (could this be a heat issue? It does get a little warm) schedule is off and settings are set to not sleep at all.

Any ideas? I pulled off the case and hit the power reset button on the motherboard, I even switched the cord to a dedicated AC plug. Stilll happening.

Any suggestions...please post..not sure what else to try....

Frank

[Captain Curt]

Frank, I am not an expert whatsoever, if I were in your shoes, I would plug in a light and your mac on the same extension cord. Know that the problem is in your computer first. If the light stays on when your mac dies then I would go Apple menu-->About this Mac-->More info-->Hardware-->Diagnostics (look OK?) then -->Power (look OK?) then-->go back to-->Software-->Logs-->Error log (Look Ok?). If you have a printer in the error log look to see if the scheduler is "shutting down normaly"? If everything looks OK look for a power selector on the outside of the mac (110 volt/220 volt). Don't know if the G5s have it, if you do unplug the power and push the selector back and forth between 110 volts and 220 volts 5 or 6 times (Leave it on 110 volts of course), plug in the power and try it. Good luck.

[P]

Search these forums before you ask. I know that I have answered this question several times already, and I'm not alone.

You have the thermal runaway problem. If the G5 overheats, the system will react by sleeping. This will give you a chance to save your work later while not damaging the CPU. Either the fans aren't working or the CPU itself is broken. In either case, it's a hardware problem that you will have to have fixed by a professional.

To confirm this for your self, read the console log. You should see something about a thermal runaway.

[Big Mac]

It doesn't sound like a thermal runaway due to the fact the OP mentions his Mac shuts off as opposed to going to sleep. His problem sounds more like a PSU (power supply unit) malfunction or a general power disruption. I would move the unit to a different outlet, similar to what Captain Curt suggests. This isn't a conventional issue.

[P]

I'm reading the posts sloppily again. Sorry Big Mac, frankmcma: If it shuts down, then I'd bet on the PSU as well, but read the logs for hints first.

[jamil5454]

Either the PSU or the source of the power coming to the computer. It could be that your PowerMac is drawing too much power at certain times (ie high CPU load) and so a breaker switches or something.