Underclocking a MAC MINI G4 to keep it cool

[gaula92]

Hello there!

As the Mac Mini G4 is getting pretty popular among amigans, I think it's a good place to ask.
I know some powerpc macs have "Apple Menu > System Preferences > Energy Saver > Options > Processor Performance", but it's not the case for my 10.4 Leopard OSX. It allows to put the CPU in reduced speed mode. That setting keeps the computer cool and the fans silent by reducing the cpu speed.
But the Mini G4 doesn't have that option, sadly...

NVedit hacks won't allow real cpu speed control, but...is it possible to fool the thing so it will show the Processor Performance options??
I only need to keep it always in reduced processor speed mode: disabling dynamic speed is a solution, but HOW?

Thanks!

[Piru]

As far as I know the only way to underclock the Mini is to change the PLL multiplier jumpers.

[gaula92]

But Piru, the MAC MINI G4 can run in reduced speed: it runs in reduced seed by default and then swutches to full speed if needed.

I only need to prevent the dynamic speed change: there must be a governor, a kernel extension...anything---

thanks!

[Piru]

@gaula92

the MAC MINI G4 can run in reduced speed: it runs in reduced seed by default and then swutches to full speed if needed.

As far as I know it doesn't. Are you perhaps confusing the fan speed changes with CPU speed changes (which AFAIK do not happen with mini)?

[gaula92]

hmmm...those fan speed changes...aren't they related to dynamic cpu frequency scaling? I believe they are...

If they aren't, how can they be avoided? by physically downcloking the G4 only??

[Piru]

@gaula92

hmmm...those fan speed changes...aren't they related to dynamic cpu frequency scaling? I believe they are...

They aren't. The fan speed is controlled by a temperature sensor directly. It has no relation to the actual state of the CPU.

The G4 used in the mini has Nap and Doze modes which are used to reduce power usage. These however do not modify the CPU clock speed. Additionally, there is no way to remain in doze/nap mode in permanent basis (you can only nap/doze when idle).

So as far as I know the only way to make the system run cooler are:

1) clean the fan assembly, aiding the air flow (if you're unwilling to open the mini you can use canned air blowed thru the vents, even that helps a bit)

2) underclock the system via the PLL jumpers.

[gaula92]

nap/doze modes are controller by the kernel then?
Or are there implementer in the processor so they are totally incontrollable? I just don't get it...

On the other hand, how durable can a Mac Mini G4 be in full 24/7 use? I heard they age pretty fast, so that's why I wanted it to run cooler.

EDIT: I found an apparent solution here:

http://www.macosxhints.com/article.php?story=20071101231643321

It seems like NAP mode can be forced from Leopard

[Piru]

@gaula92

nap/doze modes are controller by the kernel then?

Yes, but you can only enter nap/doze when you're idle. If you have anything CPU intensive running you just cannot nap/doze.

On the other hand, how durable can a Mac Mini G4 be in full 24/7 use?

I know several mac mini servers that have run for years.

I heard they age pretty fast, so that's why I wanted it to run cooler.

I haven't heard of such problems. Obviously at times some systems die but compared to number of minis out there it's only a very tiny fraction.

[gaula92]

Thanks for your help/experience, Piru! It's great to be helped by the main MorphOS-on-MAC spokesman(author?)!
If CHUD settings allow nap forcing (will test at home), I'll have solved the issue!