[OT] ibook temperature sensor

[Raf]

Ibook/Powerbookies amongst you,

I've got a G4 iBook which seems to keep going into sleep now and then.

Sys log indicates:

"Power Management received emergency overtemp signal.  Going to sleep."

I've got "Temperature Monitor" installed and while it shows me that a 
number of my device temperatures are well below the specified upper 
threshold, it does not seem to yield any readings for what it defines at 
"Processor Bottomside."

I'm dubious as to whether there is really any real overheating going on 
and wondered whether anyone knows how these stats are gathered?  I'd like 
to set my mind at ease that this one processor_bottomside stat is not the 
one which is going above it's threshold.

Any help would be valued?

Cheers,

Raf