Machine shutting down due to temperature issue

[Julio Merino]

Hello,

I have a PowerMac G5 (dual PPC 970FX 2Ghz, 6GB of RAM) and recently
installed FreeBSD powerpc64 9.1-RELEASE on it. Everything is working pretty
nicely but I keep running into the following issue (which unfortunately
makes the machine not very usable because I cannot build some software I
want):

Whenever I try to build pcre, the machine shuts down with this message:

WARNING: Current temperature (U3 HEATSINK: 82.5 C) exceeds critical
temperature (80.0 C)! Shutting down!

The few information I've been able to find online about the U3 heatsink is
that it is related to the memory... and the fact that the machine powers
down reliably during the build of a particularly memory-intensive source
file in pcre seems to explain this.

Another data point that may be related is that powerd is enabled in rc.conf
but it fails to start with:

powerd: lookup freq: No such file or directory

Any ideas about what's up with this temperature issue? Is power management
not implemented for the G5, does it have a problem or is the machine faulty?

I had Linux running on this machine for a while and I didn't experience any
such issues. Granted, I didn't build pcre, but I used it as a desktop with
other memory-hungry applications and it behaved nicely.

Thanks!

-- 
Julio Merino / @jmmv