Yes..this is a fan question..exactly the same as the OP's original tittle..but I want to give the background first.
I have just acquired (free) a MBP 3,1 A1226 15 inch version with the nvidia 8600 chip.
It was dead... been that way in a cupboard for 3 years..graphics glitches..
I booted from USB and it worked fine ..immediately...
Installed Mavericks from USB.
Great for two days..then graphics glitches again and USB boot did not work
This is when I found out about the nvidia issue. Too late for the free logic board swap so...
200deg C for 8 minutes did the trick....for now. New thermal paste and cleaned the fans and heat tubes
I have installed iStat Menus and have set it to display temps and fan speeds
Without changing any fan settings within iStat menus and running multiple threads of
the temps show as CPU die getting up to 94 deg C
Yet fan speed never goes above 2800 rpm even if left running for 10 -15 minutes.
[Edit seeing 3200 rpm now]
So that got me wondering about the default speeds and temps 'hardwired' in to the Mac.
OK, so one would assume that the Apple designers are keeping the CPU/ Memory etc within Intel design specs...but 94deg C does seem rather hot.
is there any advantage in running cooler ..I'd have thought longer life...but ??
There are all these utilities designed to speed up the fans..so who is right?
Ooops.....just about to post and the screen has scrambled and come back with frozen keyboard guess I have answered my own question..extended heat not good
Power button hard 'off ' shut it down and normal re boot. I guess this is the Nvidia graphics chip issue.
But comments welcome