Emergency overtemp signal

L

Lyra

Registered
My G4, running 10.3.5, just developed narcolepsy. Booting in safe mode, I get the repeated message 'Power management received emergency overtemp signal'. It's obvious what that means, but I have no idea what to do about it. Is it something I can fix myself - I'm not exactly expert but I have fitted PCI cards and so on - I'm looking at the innards at the moment and it sure is hot in there (and dusty ...). Or does it mean a major overhaul is needed?

Any help much appreciated. Thanks
 
Not necessarily a major overhaul, but
  1. Power down until things cool off, no warmer than room temperature
  2. Blow out the dust with canned air. Be sure and use short bursts of air to avoid spitting liquid air onto the components, the temperature shock from that couls do even more harm
  3. Be sure the air intakes and outlets are all clean and not plugged with dust, in particular check the intake on the power supply that seems to get dirtier on my G4s than anything else
  4. check where you have the computer installed to be sure that it is getting good airflow around the computer and the heat is not being trapped in a case or something around the machine
  5. Double check all the fans to be sure they are working and there is good airflow through them (depending on your Mac model there are anywhere from one to half a dozen different fans).
  6. If you have added any of those PCI cards you talked about recently they might have to be pulled if they are blocking the airflow inside the case
  7. Don't run with the case open in an effort to cool things down, it is designed to channel the cooling airflow where it is needed and that does not work when the case is open
In other words, a thorough cleanup of your Mac, internally and externally as well as its environment. This needs to be done immediately before serious, potentially irreparable, damage to the logic board, CPU, RAM, and/or hard drive occurs.
 
Wow, what a comprehensive reply - thanks so much. The machine's a couple of years old and I haven't had it open since I installed the PCI card just after getting it, so that isn't the problem and it's been in the same place all that time, on 'legs' so it's not directly on the floor. I don't suppose I'll be able to get canned air anywhere near here until next week - eugh, have to use the PC. Thank goodness for Firefox and Thunderbird!

Is it obvious where the fans are? How many am I looking for? I can see a small one on the left, but I can't see any more.

Thanks again.
 
The fan locations may or may not be obvious on a cursory inspection. The first two places to look are:
  1. One the exterior, rear, near the top of the case look for some vents. They may have a lot of dust around them, this is the power supply air intake and where my wife's G4/733 seems to attract dust like a magnet.
  2. Inside the case locate the large heat sink over the CPU(s) and look on the door or inside the case for a fan that would blow over it.
That may be all the fans you have in a G4. G5s have five different "cooling zones" arranged horizontally in the chassis and there is at least one fan for each of these "cooling zones."

Too bad about the canned air, but it is definitely the safest thing to use. An air compressor could easily be too powerful and might cause mechanical damage with a too strong blast. A soft bristled brush would take forever to use, could easily cause mechanical damage, or create a static shock that could damage components electrically. Although a small soft bristled artist's brush might be helpful in breaking up any stubborn dust clumps in the corners of the case, if used very carefully and if you avoided using it on the electronic components, and if you used a good wrist strap grounded to the chassis of your computer.

FWIW I recommend using the wrist strap any time you are inside the case, just as a matter of good practice.
 
Heh, I take my case apart (pulling everything out) about once a year to clean all the dust out. Definitely makes a difference. You wouldn't believe some of the places dust gets to, either.

Hmm, make sure your fans are working too!
 
Thanks, both, so much. I've had a cursory careful clean up just so that I can get what I was working on yesterday off the G4 and onto the iBook, and I'm amazed at how quietly it's now running, which I hope doesn't mean that the fans are kaput! And I now realise how noisy it had become – it's always been pretty noisy and I never got round to the free fan replacement so I hadn't really registered the increase.

Of course, if it's nothing major it means I have to stop gazing wistfully at iMacs and keep to my schedule of waiting for Tiger before I change machines.

Anyway, help much appreciated, and happy new year.
 
Glad to hear you got it cleaned out and working better. It's amazing how quiet the fans can be when you get all the dust off of them -- the buildup of dust can severely throw the fans off balance, causing them to be much louder than they should.

In addition to canned air, which I believe to be the best solution, you'll probably encounter some dust which just refuses to move (like directly in front of a fan or something). It just builds up to the point where it won't blow off... in cases like this, I whip out the handy vacuum cleaner, slap on that soft, fuzzy, bristly brush and hose attachment and carefully vacuum any stubborn dirt out of the machine. You gotta be careful doing this, since it's easy to knock it against delicate parts inside, but I found that the vacuum, combined with compressed air, will pretty much return the machine to a spotless state of cleanliness...
 
I'm not disagreeing with you ElDiabloConCaca, but I have to put in my electrostatic shock protection comment here. Household vacuum cleaners tend to build up substantial, and I mean BIG, electrostatic charges caused by the flow of air in the hose. So... it is absolutely essential and critical that the vacuum hose and the person using the hose are thoroughly grounded to the chassis of the computer. Not only that, even the brush nozzle of most household vacuums is pretty big to be maneuvering around inside the computer case.

A much better option is an inexpensive computer vacuum. These are often battery powered so the airflow is usually not fast enough to build up a substantial charge and the nozzle and brushes are properly sized for rummaging around in a computers guts. Still and all the user MUST use proper antistatic procedures. In other words, a good wrist strap that is firmly and correctly grounded to the computer chassis and the vacuum operator having a good grip on the vacuum and/or hose to assure everything is at the same ground potential.
 
Oops... guess I should have mentioned the shock potential...

While vacuuming the computer, I am always grounded properly (wrist straps, etc.)... I'm always grounded properly when doing anything inside the computer. Proper shock precautions should always be taken, and if one is unsure about doing something to their computer, it's best to just not do it at all.

I didn't know about the airflow causing static -- thanks for the heads up. I'll probaby be investing in a good computer-specific vacuum soon.

...still, the standard vacuum really does a good job inside there... ;)
 
One of the reasons why I remove absolutely everything. ;)

It can be a pain, but it's not difficult. Plus, it's easier to clean off the chassis itself that way.

Which reminds me, it's about time for me to clean it out...
 
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