Mysterious power problems on G4

[mcrowther]

I am at my wits end. My G4 867 will power down suddenly, especially if it has been running for a while, and the temperature of the room is above 70 degrees. I have taken it to my local repair shop, and they first replaced the power supply, no effect. They then replaced the logic/motherboard- no effect. I am going to buy a new G5 soon, but I have a very important video project on this computer that I am desperately trying to complete, but I cannot get this problem resolved.
Has anyone here heard of this problem before, and what might be the cause?

Thanks,
Matt

[crazytom]

I'm not an expert, but it sounds like your machine is overheating. You might want to pop the case open when it's on and make sure that the fan that blows over the heatsink is working. I'd also suggest downloading Temperature monitor (http://www.bresink.de/osx/TemperatureMonitor.html) to keep tabs on how hot your processor is getting. It will also keep a history for you--adjustable to up to seven days. For reference, my Dual 1GHz MDD runs around 60 degrees C and 138 degrees F.

[Dont Hurt Me]

Hey mcrowther how about some more details, does the monitor shut off? look at what crazytom said also videocard could be screwing with it, Monitor? you have anything hooked up to it? drives ,pci cards, etc? also that temp monitor is not supported in many G4s.

[krimson]

yeah, sounds like overheating.. but are you getting KP's, or just random shutdowns... it also could be a loose power cable (pin), bad outlet.. short somewhere, exposed wire...

[Calliander]

Originally posted by mcrowther
I am at my wits end. My G4 867 will power down suddenly, especially if it has been running for a while, and the temperature of the room is above 70 degrees. I have taken it to my local repair shop, and they first replaced the power supply, no effect. They then replaced the logic/motherboard- no effect. I am going to buy a new G5 soon, but I have a very important video project on this computer that I am desperately trying to complete, but I cannot get this problem resolved.
Has anyone here heard of this problem before, and what might be the cause?

Thanks,
Matt

867 would be a QuickSilver '02, correct? This could be a variety of things.

1) Are you using an Apple Cinema Display with the ADC connector? Try a regular monitor if so.
2) If your video card has a fan on it, is that one working? Or noisy?
3) Open the case while it's running and check the big fan which is on the right-hand side - is it spinning? If not, the proc might be overheating.
4) Check to make sure that the small fan (the muffin fan) next to the processor heatsink is working. It blows the air out of the machine so you should be able to tell if it is working or not. If it isn't working, your proc might be getting too hot.

Ultimately, I would try a different repair shop. It sounds like they are guessing and not fully testing the parts. You can locate another reseller or Apple Store using the link in my sig.

[krimson]

Originally posted by Calliander
867 would be a QuickSilver '02, correct? This could be a variety of things.
....
4) Check to make sure that the small fan (the muffin fan) next to the processor heatsink is working. It blows the air out of the machine so you should be able to tell if it is working or not. If it isn't working, your proc might be getting too hot.

Ultimately, I would try a different repair shop. It sounds like they are guessing and not fully testing the parts. You can locate another reseller or Apple Store using the link in my sig.

shouldn't that one suck into, and over the heat sink? cause that's what mine does. :confused:

[Calliander]

Originally posted by krimson
shouldn't that one suck into, and over the heat sink? cause that's what mine does. :confused:

Heh. They do do that. That's odd, it'd be better cooling if the air blew out of the machine somewhere. (Note that the air going into the plastic area because of the big fan doesn't really count.) I never even noticed that. However, you can feel a bit of air movement around the grille on the back near the muffin fan intake. Thanks for the correction. ;)

[jptrott]

Have you tried to reset your PRAM and/or also replacing your PRAM battery.