AMD 'cool & quiet' stopped working in squeeze (and lenny?)

[Paul E Condon <pecondon@mesanetworks.net>]

I have a made for pieces computer. One of the pieces is an Asus
M2V motherboard containing an AMD Sempron(tm) Processor 2800+

I have been running Squeeze and updating occasionally. I updated
yesterday (or perhaps day before) and there was a new kernel version,
so, of course, I rebooted. Now the fan always runs at full speed.
Before it would run a few seconds at full speed and then slow down
to a much more acceptable gentle whine. I think this has to do with
AMD "Cool and Quiet" technology, but all the hits that I get in
Google are really old and don't help me. (The only kernels mentioned
are in the K7/8 sequence which has ceased to exist, so far as I can
tell)

I think I need to tweek something that is already installed, but I
have no idea what its name is, and I have already done enough mucking
about (tried to revert to Lenny) so that I probably need to do a clean
re-install. But what Debian packages relate to AMD Cool and Quiet? 
What should I make sure to install? What programs do I run to adjust/
enable Cool and Quiet? And what is the cute Linux community name for
this stuff?

TIA
-- 
Paul E Condon           
pecondon@mesanetworks.net