Please help, G5 sounds like a jet!

Before I start, I have searched and searched and could not come up with anything here. If you do have a old link please state it to save reviving this issue.

Anyway, I run my PowerMac G5 on the 'Reduced Performance' setting to allow the fans to barely make a noise. Great for web browsing etc, but thats about it. I do a lot of Photoshop work and filters etc take ages to process on this so I have to put it on 'Highest Performance'. Whilst this increases performance 10 fold noise also becomes unbearable.

Even if I just run the cursor left to right on the dock, the fans will go on full blast and then once I stop they spin back down again. I wouldn't mind so much if it was a constant noise and it took a bit longer before it kicked in but its so intermittent and surely the CPU's can't warm up that much in 10 seconds of what must be light activity really?

If there is any thing you can think of to try, or fan controller software or really anything it would be VERY much appreciated! It's driving me nuts.

Specs are in profile, and it is the liquid cooled model.

No one got any ideas? I've since tried:

Resetting the PRAM? (cmd+alt+p+r at startup),
Resetting the SMU (internal button),
Ran Apple Diagnostics (1 1/4 hours later passed everything)

Should I try re-installing Leopard? One minute the fans are at 300rpm then they jump to 1000-3000rpm then back down again.

Have a look at this article and see if it helps. Use CHUD 3.5.2 on a FW800 G4 and it made a huge difference to heating and fan noise.

Quiet Your Noisy G5 Mac Audio Output - O'Reilly Digital Media Blog

Thanks for the link!

I will be honest here and admit I downloaded the app quite a while ago - I think I even read that article! - anyway now I've unchecked it again and the fans are about 1100rpm constant. +900rpm over normal.

I ran a quick 'lens blur' on a 12MP photo in Ps CS3 and the fans ranged between 1600 - 1100 which to me is a success as the difference is barely noticeable anymore! This was over a 15 second time frame, although before it would go to 3000rpm then take ages to spin down to 300rpm so the noise was harsh.

I suppose disabling a processor would help cooling too, but I don't want to keep turning CPU's on and off constantly.

Thank you for reminding me of the feature, maybe preforming the steps in the second post did something to the Processor app as it didn't work before!

Hmm, maybe I should recommend that article to my colleague... his G5 is really noisy as well!

It's funny Apple spent so much time going on about the G5's "thermal engineering" back when they were released... they didn't really do that great a job!?

Couldn't agree with you more Aptmunich. The thermal zones can't cool 2.7GHz quitely, even with liquid cooling they still run 70oC as I'm typing this!

If that was Intel it would be melted into the socket.

Considering that its meant to be 'Silent' to run it without having a hurricane starting under my desk I need to run the fans at 1300rpm which, while far from loud is hardly silent!