cpu usage

[gareth]

hi, i'm on FreeBSD 6.1, with a problematic cpu - it seems
to be overheating and shutting the system down when running
intensive jobs, at the moment i can't even finish compiling
the mysql-server in ports. i've tried running the make with
an increased nice level, but that doesn't seem to change
much. and looking through ports there only seems to be
cpu monitoring tools, not suppression?