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Quad G5 - Fans running > 3000 rpm, CPU B overheats to 100 degrees

This machine is now about 2.5 years old, and the fan noise has got louder since I bought it. The last few days, the fans have been blaring away at full speed. I installed Temperature Monitor, then to get better info, iStat. Right now, with only one Safari window open, CPU A is showing two temperatures below 35 degrees centigrade. B is hovering around the 60 mark, i.e. double. The CPU is reporting 97% idle.

I opened the case and cleared out all the dust which had accumulated inside. There was a fair bit. I generally open the box every 3 months and clear out. This didn't make any difference whatsoever.

Thsi afternoon, things got worse. The system began going to sleep while I was using it. I checked the logs, and they were showing CPU B hitting 99 degrees centigrade and forcing sleep in order to save itself.

Up until last week, I had the performance of this box set to Highest in energy saver, and never turned it off -- only rebooting for the rare crashes (like 3 a year, at most) and software updates. After seeing my most recent electric bill, I changed my settings to Automatic and set the Mac to witch off at midnight and start up at 8am. Apart from that there has be no change in usage, nor have I installed any new software or hardware.

Following the forced sleep, which happened this afternoon, I have set performance to Reduced, disabled the screen saver, told to computer to auto sleep after 30 mins inactivity, and sleep the display after 15 mins. I have re-enabled the setting to sleep hard disks when possible. I even used the processor pane from CHUD to disable cores 3 and 4, but this seemed to do very little for the temperature of CPU B, so that's been re-enabled.

Following other advice, I have rest the PRAM and NVRAM, reset the SMU, and removed every device from USB and FireWire bar the keyboard, mouse and monitor. I ran the Hardware Test in full. It took over three hours but reported everything as OK, RAM, Logic Board and GPU. Disk Utility verified both hard drives as fine.

I am dreading hearing that CPU B is failing, and find it hard to believe a machine less than three years old, sold as a professional workstation, which cost me £3,000 and took me two years of a very expensive loan to pay off, would have this kind of catastrophic failure.

Is this going to cost me a lot? Have I just been taught the hard lesson that you don't get what you pay for anymore? I love my Mac, but if it costs me the price of a new PC to replace a part, I'd be very upset.

Can someone recommend any further diagnostics or a possible explanation and solution? Do I just need to bite the bullet and get to the local Apple Centre?

Thanks in advance for any help you can provide.

Powermac Quad G5 @2.5GHz, Mac OS X (10.4.11), Geforce 7800GT, 6Gb RAM, 2x250Gb SATA HDD, 20" ACD

Posted on Jul 23, 2008 12:44 PM

25 replies

alan_moore Author

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Jul 25, 2008 12:27 AM in response to Samsara

The disk is the authorised Apple repair disk. I may give it a shot once I have it.

The nearest Apple store is quite a distance -- it's a 45 minute drive away, and in a shopping centre, so I'd have to find a way to lug that heavy g5 tower round to the upper floor. I can see me making the trip, but seeing as petrol is currently the equivalent of 8 to 9 dollars per gallon in this country, I'm not eager. Going to have to do it, I guess.

I am stuck with the Mac, I'm afraid. I use it to work from home, and the company I work for has provided me with the full Creative Suite for Mac. If I change platforms, they have to buy a PC edition for approx. £1800. They won't do that. Unfortunately, neither will they cover the cost of my repairs. Instead, they will lease a Mac Pro and I'll have to work in the main office! Not what I want to do, frankly. And it doesn't help me get my Mac fixed.

I do feel burned. I bought the Mac on the evidence of the G4's in my previous workplace, many of which were only retired last year, after 7+ years of faithful, hard-working workstation service. I had one opportunity to buy a new computer, and at that point could have gone either way - Mac or PC. After years of PC frustration (I used to build them for a living), and a couple of years of professional Mac use (I had fallen in love with the way Tiger works), I knew it was worth buying a Mac, and spending as much as possible to get the best one available. It's taken me 2 years to pay off the loan for this machine -- it only finished in May.

Currently, PCW Business are selling HP workstations for £700. They are quad-core, have 4 gig of RAM, and look reasonable. They also come with 3 years one site warranty.

I'm going to give Apple a call and talk to their customer services. I'll see if they will help. I hope so, because I'll be really upset to have to wave goodbye to this Mac, but if repairs come in at a price too close to the cost of that HP workstation, I'll plump for the item with three years' coverage, and work from my main office 😟

Samsara

Level 4

1,327 points

Jul 25, 2008 1:10 AM in response to alan_moore

Morning Alan,

Remember to call ahead for an appt. before you go. You might also ask them then if they could take that cover off without charging you. It should be very easy for them so I don't see why not. And also ask them if they can provide a cart for you once you get there, they are a huge pain to lug around.

If your Mac can be fixed economically that would be great. If not there is another option before getting a PC. Getting a used MacPro. I don't know what they are going for but it might be an option. Check out prices near and far. Sometimes you can get some pretty good deals here in the US. Granted shipping might cancel those savings out.

Apples not really in the business of helping their customers but you never know. They have provided new computers to some users under certain circumstances in the past. Worth a shot, maybe they'll bargain.

I wish you luck. Post back if you will. I'd really like to know how it all turns out.

Samsara

Level 4

1,327 points

Jul 25, 2008 1:53 AM in response to alan_moore

Here's a link you might take a look at. Though I'm not sure you are in the mood...

http://lowendmac.com/dealers/index.shtml

Edit: A dual core on this page. Your RAM might even be compatible, not sure though.
http://www.macbooty.com/index.php

Message was edited by: Samsara

alan_moore Author

Level 1

0 points

Jul 25, 2008 5:07 AM in response to Samsara

I think I have been very lucky here. I feel sorry for others with the same problem, though, as my solution will be no help to them.

When I ordered this machine, it was delivered DOA. The power supply was dead. I called up Apple and they sorted out a new machine for me, which is the one I'm now having problems with.

I called Apple tech support today, and they informed me I still have 8 months Applecare on my G5. It appears that Apple added three years cover to my replacement G5 after the failure of the first one -- something I had not been aware of.

So, the good news is that my Mac will be repaired and in full health, for free! 🙂 🙂 🙂

However, I have been very lucky.

If I come to buy another Mac in future, I will pay for that extended warranty. :P

Samsara

Level 4

1,327 points

Jul 25, 2008 6:00 AM in response to alan_moore

Alan,

I'm very happy for you. Please post what they do to fix it or if they replace it. That information may help others.
Also, I'm baffled... You must have bought Applecare when you got the machine. You said your Mac was around 2.5 years old. You probably had coverage regardless of the dead power supply...

alan_moore Author

Level 1

0 points

Jul 25, 2008 9:49 AM in response to Samsara

Nope, I definitely didn't buy Applecare. As I said, the G5 was DOA, and now I try to think back, I believe they automatically added Applecare to my Mac for the extra week I had to wait to get a working machine.

I will be sure to post all details here. Like I said, the fact that I've been lucky doesn't help anyone else, but hopefully the information I get back might.

I shall spend the weekend backing up, then get it sent off, probably Monday or Tuesday. As soon as I know more, I'll post it.

Samsara

Level 4

1,327 points

Jul 25, 2008 11:13 AM in response to alan_moore

Yes, I'm sorry I didn't read your post more carefully. I wonder why I didn't get that deal when my Dual 2.0 was dead out of the box... as well as the next one I exchanged it for. That one I had fixed by an Apple Repairer. Still, It died about two years ago after I put Leopard on it.

I guess I couldn't believe that Apple would be so generous. Applecare's a good hunk of change.
However... could it be that this link is applicable to your situation?
http://www.apple.com/support/powermac/powersupply/repairextension/

alan_moore Author

Level 1

0 points

Jul 25, 2008 11:35 AM in response to Samsara

I had looked at that -- my serial number begins CK611 but it may be that the first G5 I was sent fell into that category since that's exactly how it was when it arrived.

I think I just made a fuss when I was on the phone about the crippling load I'd had to take to pay for this £3,000 computer, and how disappointing and surprising it was to have a dead machine from such a renowned manufacturer, etc etc. and the nice Irish fella on the other end upgraded me to what the support pages refer to as a 'custom support plan.' Basically I don't have Applecare, but he extended my warranty by 1000 days, so it's the equivalent.

I wish I'd remembered that earlier -- would have saved me a few sleepless nights 🙂

alan_moore Author

Level 1

0 points

Aug 13, 2008 5:57 AM in response to alan_moore

I spoke to the Apple Tech yesterday. Turns out one of the CPU sensors was faulty, hence reporting the 20 degree temperature difference. In a genius move, whoever designed the G5 processor decided to make it impossible to work on, so they are fitting a complete CPU unit -- 2 processors, heat-sink and water cooling piping, the whole thing.

It should have been fitted yesterday, tested today and hopefully back at the shop for me to collect by Friday, maybe Monday at the latest.

Incredible that it was designed in such a way that a faulty sensor could cause £700 worth of repairs! Lucky for me, it's all covered. I hope the new processor has 12 months warranty on it, but I'm not sure.

I'd just like to thank everyone who responded to my questions. This is what I call a real community. You have all been very friendly and helpful. I hope the information I've provided here can help someone too.

alan_moore Author

Level 1

0 points

Aug 17, 2008 4:36 AM in response to alan_moore

Well, I'm writing this from my repaired Quad G5, and it's doing great. Even slamming the processors to get them all at 80-100%, the fans stay quiet and the chips all register at 70 degrees or less. Most of the time, they idle at 40 or 50 degrees. Seems the sensor was reporting CPU A at 10 degrees less and CPU B at 10 degrees more, causing the issue with the fans.

Even better, there was no call to reformat the drives, etc so it was delivered as I left it. I just reinstalled my data drive into Drive Bay 2 and it's like it's never been away. Forgot how quiet this thing was when I bought it -- this problem has most likely been coming on for quite some time.

Now I'm a happy Mac customer 🙂

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Quad G5 - Fans running > 3000 rpm, CPU B overheats to 100 degrees