Fan Control For PPC Mini?

I'm not aware of any means to control the fan of a PPC mini, since unlike the Intel version, it's not controlled by a system management component.

I would also say that even if there were a way to control the fan and make it run slower or trigger later, I would advise strongly against doing so, simply because the fan is designed to cut in at a point where the mini needs the extra cooling. Delaying it's action or reducing it's speed would risk the system overheating.

I think it's more sensible to look for whatever reason the fan is cutting in so frequently, because it certainly should not, as a matter of normality, ramp up unless there is significant load on the system. Flash can cause that in itself, but your '..getting tired of the fan spinning up for every little thing....' suggests it's more of an issue than just Flash or other such items.

I would suggest you download and install a simple monitoring utility such as MenuMeters (from www.versiontracker.com) and enable all the metering options. This puts a series of meters in the menu that allow you to see what the CPU load is, what disk read and write activity exists, how busy the system is paging, what memory is being used and what network traffic there is - all without causing notable CPU load itself. When the fan spins up, if the CPU load isn't running fairly high and/or the system being kept pretty busy with paging or suffering heavy memory usage, then it would suggest there's an issue with the mini's hardware.

If that is the case, a PMU reset may well help, but other than that, check the obvious such as airflow around the system, and that the vents are clear, both around the base and the outflow on the back.

To reset the PMU if you need to:
- Unplug all cables from the computer, including the power cord.
- Wait 10 seconds.
- Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.
- Let go of the power button.
- Press the power button once more to start up your Mac mini.

Excerpt:
"It seems a bit extreme - just putting even a
little stress on the mini revs up the fan. It doesn't
seem to be for heat, but for processing speed. The
more processing power needed (like for interpreted
languages), the more the fan revs."

What interests me is that neither of my G4 minis exhibit this behavior - in fact I haven't had the fan rev up on either of them, even under notable load. However, the comment is correct in a broad sense that the fan doesn't really respond to heat but to CPU load - basically if it were geared to a climb in temperature, by the time the sensor noted a rise sufficient to trigger it, the fan would be too late to control the temperature rise. Thus the fan is rather more triggered by CPU load, which allows it to spin up in anticipation of a temperature increase caused by a prolonged high load. This is also why various MacOS updates have altered behavior of the fan, because basically they have changed the algorithm for triggering it - typically making it more responsive in order to lower the risk of the system being driven into overheat.

That said, Flash is known to push CPU load up and keep it high, so I'm not entirely surprised that it might trigger the fan - at least at the outset of processing Flash content. If this were the only point at which your mini spins the fan up, I would say you likely have nothing wrong as such. In that situation, you might try YASU (downloadable from www.versiontracker.com) and set it to clean system caches. That may help slightly decrease the CPU load on commencing the processing of Flash content.

I'm using Safari with Pithhelmet and the Flash/Fan
isn't an issue in most cases. I don't consider the
fan revving a problem per se, it's function seem
normal, but still it's interesting to know if it's
really needed that bad and having no possibility to
monitor the CPU temperature doesn't help.

Do you happen to know what the temp. limit is on the
1.33 PPC CPU? Perhaps it can run with the fan
disconnected (for test purpose)....

The only temperature sensor in PPC mini systems is on the hard disk, and can be measured with Temperature Monitor Lite (downloadable from http://www.versiontracker.com/dyn/moreinfo/macosx/19994). This doesn't really help all that much though because CPU load doesn't necessarily reflect any condition which affects the drive. When monitoring my own system, the sensor read 39.0c regardless of CPU or drive activity levels, rising just 1 degree after 5 minutes heavy use.

I'm currently using Onyx with the Automation function
for easy cleaning, thanks for the tip about YASU, I
will check it out.

I would urge you NOT to use OnyX or any similar utility on a regular or routine basis. MacOS should not need any routine attention of that kind, and if it does then it is indicative of something that needs attention. The reason for suggesting YASU to clean system caches in this instance is that I have encountered Flash issues in the past where abnormally high CPU load were caused by a cache which had been damaged.

Interesting piece of software!