Fan randomly running loud + computer not responding

Question

I have been facing a problem for the last several weeks on my PowerMac G5 that technicians have not been able to solve either.
The computer randomly stops responding and the fans start accelerating slowly until they reach their top speed and then stay at that speed for indefinite periods of time. I cannot see any pattern in this - it happens both when the computer is running some process and when it is idle.
Each time this happens, the only option for me is to do a hard powerdown (hold down the power button).
I saw another question about fans running at high speed, but that case, it seemed as if the computer continued to respond.
Any help on this would be appreciated.

Answer 1

I am having the same problem.
Now before you start taking advice to back up all your data, reformat your hard drive, and reinstall all the software; please take note of a few things:
first off, I'm disappointed/frustrated/melancholy that this is happening to me. I spend $5000+ for a "reliable" Apple computer. Then it doesn't want to turn on because its not safe. Sorry if I drown this post with bitter sarcasm but I am coming to the end of the line with my patience.
I called Apple Care, read a bunch of posts (here and elsewhere), and yes I do know about the SMU Reset button (like that really does anything?).
My problem happened a few weeks ago and I thought nothing of it at first. There was a power outage for a quick second and it turned everything off. When I went to turn on my computer, there was no chime, the red light was on, and the fans were running and eventually began running very loud. After letting it run like that in hopes of the screen lighting up, I turned it off by holding the power button. By the way, there's nothing on the screen and the keyboard doesn't work (I use a wireless keyboard, but I plugged in the OG cord keyboard to push whatever series of buttons recommended by these "geniuses") Trust me, the computer doesn't make it to that part of the boot process, so stop with commandoption+PR or F12 to get the CD out. It doesn't work! What's up with this computer! It can handle all these intense calculations,etc. but a power surge is going to shut it down indefinitely.
So I left the computer came back the next day, turned it on and its fine. Cool, I'm happy. It's Working!! I go on a few weeks, then I go to turn it on this Monday, same problem. But actually a worse situation. I had a client come over and the computer wouldn't work. I looked like a idiot. Couldn't do anything cause my computer didn't want to turn on. I do music production/editing. I use my G5 for running ProTools LE. I have other programs but that is the main one I use. There's nothing wrong with it. It's optimized for use with the mac. So those people who are going to advise me to uninstall all my software and all that - I appreciate your concern but don't give advice when you don't know anything!
So I am getting frustrated. My client left a little disappointed, but what can you do? I tried to call AppleCare on Mon. but it was Memorial Day. So I waited for Tues.
Tues morning, my computer turns on like everything is fine.
I'm happy but cautious. I talk to AppleCare rep. He tells me that it is a common problem they have heard about with the G5's. Wherever blackouts, brownouts, spikes, sags, dips, and other electricity inconsistencies occur, the Power Mac G5 has a breaker in it which flips so it doesn't receive uneven power supply and damage internal components.
I like that feature. Good thinking Apple. Protecting my investment from bad electrical grids. But I don't like the fact my computer has a mind of its own where it decides when it wants to boot or when it wants to sit there and run its fans all loud.
I shut down Tues morn to go to work. I come back in the evening, it doesn't want to boot up. Instead of getting angry trying a bunch of times to turn on/turn off the computer, I leave my house all together and go and have a few drinks. I come home ,don't even look at my computer, and go to bed.
I wake up Wed. morning. Go to turn on my computer. Successful boot. It's running. Okay, I think, I'm going to get down to the problem. I read all the logs, not like I know every piece of info, but just to see what's happening. Everything looks fine. I decide to run the AppleCare CD Tech Tool. It says restart holding down C. I do that. When the gray Apple Logo comes up, all this writing about kernals comes up and it tells me to restart or shutdown. I shutdown and attempt to restart, same problem: no chime, red light on, and fans eventually spin loud. Now the CD is stuck in there. I'm going to take it to the Apple Store tomorrow to if these "geniuses" can figure it out.
(Just a side note: Apple calls them geniuses, but its hard for me to think some disconnected college kid with a bad haircut and questionable social skills knows what's up with the power supply issues of a computer; maybe I'm wrong, but you can run your diagnostics and look at the chart of what to do and all that BUT Apple needs to listen to the people)
I am going to get a UPS (uninteruptable power supply) with a clean sine wave output to curb the issue at my end. It's not my fault I live in a area that receives uneven power output. I live in Los Angeles. Summer is starting up and I think its going to be hot, so blackouts, power dips and sags are inevitable. I just don't understand why Apple hasn't considered this problem and fixed it with something:
A recall to change the power supply, Is it something on the logic board?, are they going to reimburse me for lost income (Ha, yeah right)
I really want to know how many people are having this problem?
From what I've heard, it is a common problem.
So I think we need a common solution.
If its so common, it must be the computer. We are all going to live in different areas where the power may vary. Not all of us have the consistent power flow of 1 Infinite Loop in Cupertino, CA. So if it is such a common problem, Apple needs to fix it.
I can't spend more than five grand on a super duper computer and have it wuss out on some power issues.
Its a loss of income and productivity to me.
I can't have that anymore.
Sometimes my computer turns on, sometimes it doesn't.
I bought my PowerMac G5 in April 2006, its been about a month and a half and I'm having these problems.
Thank you for your time.
If anyone else has been having this problem, I feel for you.
It was been very difficult for me not to curse in this post, but I have tried to extend the same respect to all that use these discussion boards to create dialogue, find help, and create solutions.
LETS FIX IT!
Peace,
Swami G
Power Mac G5   Mac OS X (10.4.6)   4.5 Gb RAM
Power Mac G5   Mac OS X (10.4.6)   Dual 2.3 GHz / 4.5 Gb RAM
Power Mac G5   Mac OS X (10.4.6)   4.5 Gb RAM