Got KarmA?
As said in the PM reply to you, others asked me so I've put details here. Can't give you a direct link as you need to start a session, so go to
www.rswww.com
On the front page top left search box paste in this code
183-559
there are a few to choose from but they all do the same thing.
It could simply be set up using a system fan with rotational detection on the CPU header to shutdown the system on low level, in exactly the same way as my no-flow detection detailed in this article
HERE
I'll do a simple circuit diagram if you need.......