Mac G5 Revving Up

The SMU (System Management Unit) might need resetting...

http://support.apple.com/kb/HT1436

Is there a disc in the disk tray?

You have a liquid cooled Mac, which typically always revs up quite a bit under load.

Couple things to look for:
1. Dust in the machine; this can kill your Mac & power supply. Clean it out if needed. You can also remove dust from the power supplies fans without disassembly if you have a strong vaccum cleaner. The dust will collect around the fans in the lower front corner by the bend. Yu can suck the dust right through the holes from the outside.
2.Check for spilled cooling liquid. See if there is corrosion by the lower rear of the machine (by the rear cpu cover & fan). If so, this will be expensive. Early discovery will save important parts.
3. Could be rogue processes when running the machine. I would install the free iStat Pro widge, which shows fan speed, temperature, load & processes.
When your fans speed up, launch the tool.

Hope this helps,

Wolfman

He'd only have the liquid cooled mac if his model was a Dual Core Dual 2.5.
http://support.apple.com/kb/SP37

Incorrect. The only liquid cooled Dual 2.5GHz machine that Apple made is a dual processor machine.
June/Late 2004 model. You are referring to the Quad core

Correct.

The original DP 2.5 G5 has liquid cooling, and incidentally is the machine I am using.

I think the only liquid cooled G5s were the 2.7 and then the next series of multi-cores. You're saying that the first G5s had it then Apple dropped it only to reintroduce it later?
http://support.apple.com/kb/SP80
http://support.apple.com/kb/SP67

I misspoke about it having to be a dual core, dual 2.5. I should have said the Quad, but he doesn't seem to have one of those either.

The poster might try starting in safe mode and see if the sounds persist. Could be some kind of software scheduling that starts up every now and then.
http://support.apple.com/kb/HT1455

Samsara,

Apple introduced liquid cooled processors to the top-of-the-line models in mid 04, which was the 2.5Ghz (single core) dual processor. The late 04 model is identical (no changes).
They continued this approach until the end of the G5 series; lower-end models are air cooled, the top model liquid-cooled.
For early 05 it was the Dual 2.7Ghz, for late 05 it was the Quad 2.5Ghz.

Wolfman

Hi again Wolfman,

This page is the only place where I can tell for sure that at least the 2.7 had a LCS. It says it on top.
http://support.apple.com/kb/SP46
The final series of multi-cores doesn't specifically list it but they all have it.

You may be right, but it doesn't sound right. I thought that liquid cooling was Apples attempt to address heat concerns in the earlier models. Not to doubt you, I have a lot of respect for you from our last discussion, but how could we check for sure? Ah, amongst other ways I could try this and not continue to hijack this thread. Keep an eye out for a new G5 posting...

Samsara,
If there is one thing that I don't rely on is the completeness of Apple's own specs. They are not wrong, but what is listed on the website is part of their prior marketing materials and as such don't focus on exact details.

Re. the Dual 2.5's, we have several of those and I had several with liquid coolant leaks, so this knowledge is based on unfortunate hands-on experience 😉

Also, of the late 05 series of dual-core G5's, only the Quad has liquid cooling. The 2Ghz & 2.3Ghz use traditional heatsinks.
Liquid cooling systems are very expensive and were always reserved only for their most expensive models.

Wolfman,
I was going to write and ask you if you had indeed worked hands on to know for a fact what you're saying, but I didn't want to keep hijacking the thread.
Well, that's very interesting... you caught me with my ignorance pants pulled over my head. Thanks for correcting a long standing misperception I had. 🙂

Check out my new thread and reply if you will again, treats may be in store...
http://discussions.apple.com/thread.jspa?messageID=8212057#8212057