well... on your 2.nd Q.: some people put their box in the freezer, but in your case, i would just remove the casing.
and if you want to change the thresholds, i think you have to go to the bios-setup utility, available at boot( hitting " del " or " F2" , it's pointed out on the screen at boot ) and change that settings.
egag
edit: for the messages look in /var/log/messages
