All fans run when g5 idle - Can root level editing fix this?

[kifkif]

I have a g5 late 2005 dual core 2.3Ghz power pc. Leopard 10.5.8
I recently bought this, and could really do with some help understanding this problem, please..
All the fans come on the moment I press the on switch. I've tried many things - listed below, I've read zillions of threads on g5 fan issues,
and now I've purchased 'hardware monitor' software, and found all sensor temps cool; and all fans are running. All are running at/near enough at the 'minimum specified rpm' which is handily also listed for each fan in this software. (but the noise level is about 3 times louder than my g4 - which I'm upgrading because it's so noisy!).
I have briefly tried two of the earlier G5's, a dual 2.3, and a dual 2.5 (neither dual core), and they are both relatively completely quiet - no fans from switch-on at all, obviously they start to come on once there's a load on, but otherwise, no fan noise when idle.

Question1: Is this (on all the time, at min speed) how they are supposed to run on this model of g5? surely not, 3 times louder than a g4?
Question2: Can I reset the min speed, or some other edit to stop them being on all the time, through root- level editing?
Question3: If so, what are the operating temperatures/minimum speeds they should be re-set to, in order to function well and safely?

I've seen from forums that it's possible to adjust the inner settings of the 'thermostats' or temperature levels, that trigger, and ramp up, the fans, and also the minimum fan speed, but everyone on those forums wants to use this fix to increase fan activity. I want mine to stay still, or slow, until they are needed!

Any help with this would be massively appreciated, as I bought this computer 10 days ago and must decide soon whether it's fudged and has to go back!
Many thanks for reading this far!
kk

Things done so far:
Since buying it I've wiped and re-installed, and updated OSX leopard - which fixed another issue of fans staying on, and speeding up, during sleep.
Tried it with all connections removed, all pci-e cards removed including the graphics card, all extra memory removed, even with a blank HD - no OS installed. tried booting from DVD.
I've cleaned it, checked the seals, reset everything, checked for firmware..

 

[alust2013]

They all should be running at min speed from powerup. Perhaps you just have noisy fans?

 

[kifkif]

Hi, thanks for your reply.

Surely not this loud? It's about 20 times louder than the other g5's I've tried, and three times louder than my g4 dual 1.0Ghz.

Maybe the minimum speed setting is too high? They are clocking between about 1000rpm and 1600rpm each fan on minimum, and there are about eight of them.

 

[kifkif]

Actually, I've just cross-referenced min. fan speed readings with info in an older thread, and mine are all normal - between about 500rpm and 1600rpm for the record.
So maybe I do have a/some noisy fan/s in there. I didn't think worn bearings would be that noisy. Just goes to show.. Now I need to find some replacements I guess. Any ideas out there?
Thanks again,
kk

 

[kifkif]

Progress update:
I started another thread: Replacing worn fans on G5 DC 2.3. What exactly do I do?:
https://forums.macrumors.com/showthread.php?p=12704559#post12704559
And got a mindblowingly comprehensive reply!
One tip in there was to stop each fan with your finger, to find the noisy one/s.
Bingo. Just one fan is noisy - not due to wear, but because it's rotating at, or somewhere near, maximum rpm (circa 3200).
However, Hardware Monitor reports it as operating at minimum rpm (circa 500rpm).
So.. I'm starting a new thread, as the title of this one doesn't fit anymore..

 

[bbh1031]

The G5 may require a "thermal calibration" which can be performed via an "Apple Service Diagnostic" program, an open firmware program "not available to the public."

If the processor was removed or replaced before you bought it, thermal calibration is necessary.

 

[VanneDC]

mate, have you got the see-through plastic wind shield that fits inside? theres a sensor on there somewhere that if its not in makes all the funs run flat-bicki.

 

[bbh1031]

The sensor is a white label-like sticker on the far right tab at the bottom of the plastic side case. As the previous poster said, if that sensor falls off, the computer assumes there is no plastic side case on and it makes the fans run full blast. You can stick some tape on the tab and color it with a marker and it will work again. That has worked for me.