G5 fans on full

Hi

I have a G5 1.8 single. I bought it used about 6 months ago, the fans have always been noisy and stupidly I never really looked into it until now (got ear ache!)

I have this data from istat pro:
CPU B Intake......1000rpm
CPU B Exhaust....1000rpm
CPU A................3700rpm
CPU A Intake.......3200rpm
Drive Bay...........4000rpm

It seems some of them are running fast/on full?
So far I've tried, resetting the PRAM, the NVRAM, tried changing the 'energy saver processor preferences' and taken a look to see if there are any visible problems, ie dust or blockages.

Any other ideas guys?

Yep, those look pretty fast. My G5 Drive Bay is 1000 RPM, my CPU intakes are 499, my CPU exhausts are 515 RPM.

Other than the noise, is the machine working well? This seems very unusual? I would wonder about a possible sensor fault if all is working well.

Yes, all is working well, I use the mac 5 days a week, 8 hours a day with no problems apart from making my ears bleed. The temperatures and fan speeds are pretty consistent. The fans come on full as soon as I boot up and don't stop until I shut down.

Since you have already done all the usual things, in terms of checking for mechanical cooling system blockages, I would recommend that you do your ears a favor and take the machine in for service. My PowerMac is blissfully quiet. It is one of the most quiet computers I have ever used. There is no reason you should have to endure that aural abuse!

macacomoco said:

Hi

I have a G5 1.8 single. I bought it used about 6 months ago, the fans have always been noisy and stupidly I never really looked into it until now (got ear ache!)

I have this data from istat pro:
CPU B Intake......1000rpm
CPU B Exhaust....1000rpm
CPU A................3700rpm
CPU A Intake.......3200rpm
Drive Bay...........4000rpm

It seems some of them are running fast/on full?
So far I've tried, resetting the PRAM, the NVRAM, tried changing the 'energy saver processor preferences' and taken a look to see if there are any visible problems, ie dust or blockages.

Any other ideas guys?

Click to expand...

Update the firmware. http://www.apple.com/support/downloads/powermacg5late2004firmwareupdatev11.html

(there may be later versions as well)

Did you say it's a single processor machine, because if it is I'd like to know why the CPU B fans are even running!

I finally fixed my twin G5 fans by doing a totally clean install of OSX Tiger after doing the firmware update, that was about 2 years ago and it has been fine ever since.

Amen-Moses

Amen-Moses, the firmware upgrade note doesn't mention anything about fans. What has caused you to link the two together?

Firmware upgrades are frequently risky - I would hate to recommend it unless it is really necessary. A failed firmware upgrade can render the machine unbootable...

Thanks for the replies.

Yes, it is a single processor, I wondered the same thing too about why all fans are running?

I'm also pretty sure it's a hardware issue as I started the mac off a system disc and the fans are still on full, this would rule out a software issue.

I also phoned up the people that usually look at my mac, who told me that this kind of thing is something they don't look into

May mean I need to send it off to Apple, I really could do without that though as it's my main mac and I work from home.

mac57 said:

Amen-Moses, the firmware upgrade note doesn't mention anything about fans. What has caused you to link the two together?

Firmware upgrades are frequently risky - I would hate to recommend it unless it is really necessary. A failed firmware upgrade can render the machine unbootable...

Click to expand...

A couple of years ago the fans issue was a big "hot potato" on all the G5 machines and in particular Apple released a firmware fix for the server range specifically to deal with the fan sensor code problems.

At about that time they also released a firmware update for my twin G5 which didn't mention the fan fix but certainly seemed to fix my fan problems.

Amen-Moses

OK, makes sense.

I do recall reading lots of reports of "full on fans" before I purchased my PowerMac, and being worried about it. I decided to take the risk and it has worked out just fine.

If what you are suggesting happened that way, the firmware fix would have been included in my PowerMac since it was manufactured AFTER the fix you mention.

I guess if macacomoco is faced with the alternative of sending the Mac away to Apple for repair or attempting the firmware upgrade, the firmware upgrade seems a sensible first choice!

So macacomoco, back up everything first, then try the upgrade. If it fails, you are still in need of sending the machine to Apple. If it succeeds, and it doesn't resolve the problem, ditto. If it succeeds AND it fixes the problem, you are ahead of the game. You have nothing to lose.

I've just found this:

http://www.apple.com/support/downloads/powermacg5firmwareupdate.html

It is for the very early G5 systems but it does actually mention fan behaviour.

(if your firmware is later the updater will not install so it is safe to try out these updates, just make sure you do not switch off the machine while the updater is running if it does need to install it)

Amen-Moses

I backed-up and tried the firmware updates but it said the updates were not needed.

One thing that I can't believe I never noticed before is that I've just realised although I have a 1.8single processor, the mac case if a 1.6 (it only has the 4 ram slots). Could that be anything to do with the fan issue?

Here is the hardware overview:
Hardware Overview:

Machine Name: Power Mac G5
Machine Model: PowerMac7,2
CPU Type: PowerPC 970 (2.2)
Number Of CPUs: 1
CPU Speed: 1.8 GHz
L2 Cache (per CPU): 512 KB
Memory: 2 GB
Bus Speed: 900 MHz
Boot ROM Version: 5.1.5f2

macacomoco said:

I backed-up and tried the firmware updates but it said the updates were not needed.

One thing that I can't believe I never noticed before is that I've just realised although I have a 1.8single processor, the mac case if a 1.6 (it only has the 4 ram slots). Could that be anything to do with the fan issue?

Here is the hardware overview:
Hardware Overview:

Machine Name: Power Mac G5
Machine Model: PowerMac7,2
CPU Type: PowerPC 970 (2.2)
Number Of CPUs: 1
CPU Speed: 1.8 GHz
L2 Cache (per CPU): 512 KB
Memory: 2 GB
Bus Speed: 900 MHz
Boot ROM Version: 5.1.5f2

Click to expand...

Interesting, I wonder if the previous owner had a CPU failure and when it was replaced the CPU sensor wasn't correctly connected or something?

I'm not sure how the connections work on the G5s as I've never been brave enough to try and remove one (especially seeing as how mine is the Dual CPU model, there is hardly any room at all i the CPU part of the case).

Have you tried finding a temperature sensor reading App for your model? If the CPU temperature sensor is reading something funny that would be a start.

Amen-Moses

macacomoco, I am not sure I understand what this:

although I have a 1.8single processor, the mac case if a 1.6 (it only has the 4 ram slots)

Click to expand...

means. Can you elaborate please?

mac57 - sorry, my bad typing. What I mean is that the actual mac itself says 1.6 on the case and is the 1.6 model because it has 4 ram slots (not 8 like the 1.8) but the processor is definitely 1.8.

Here are my temperature readings:
CPU A.........49ºc
CPU A Amb..18ºc
Us heatsink..35ºc
Drive Bay....24ºc
Backside.....17ºc

macacomoco said:

mac57 - sorry, my bad typing. What I mean is that the actual mac itself says 1.6 on the case and is the 1.6 model because it has 4 ram slots (not 8 like the 1.8) but the processor is definitely 1.8.

Here are my temperature readings:
CPU A.........49ºc
CPU A Amb..18ºc
Us heatsink..35ºc
Drive Bay....24ºc
Backside.....17ºc

Click to expand...

That' a cool backside! :tusks:

I can't really see this being a hardware problem as the sensor readings all look about right and the fans are under software control, about the only suggestion I can make is to try a completely clean install of OS X and see what the fans do before you install any updates.

If you only have one HD you could buy another one and swap them (i.e remove the one in there and put the new empty one in it's place), then do the clean install to the new drive and go from there. (SATA drives are pretty cheap at the moment)

If that fixes things then you will know that it is definitely a software problem and if it doesn't you'll at least have more drive space.

Amen-Moses

Good idea Amen-Moses. A clean install is good final step. My money is on a sensor failure though. I smell "hardware problem" here. I hope I am wrong though!

I have another hard drive I can take from my other mac but I've already tried starting up off a start-up CD and fans still come on full. I presumed that starting up off the CD would be a sufficient test?

If it is the sensor, what does this mean, a repair job can be done on that part or would I need new processor?

A repair job on the part itself should do the trick.