well, peltier, a french scientist noticed that when you run a current through two dissimilar metals you get a hot and cold side. That is what a peltier is, you have one side that gets really cold, and one that gets really really hot. You put the cold side on the cpu, the hot side preferably onto a water jacket, and you can get your cpu into the negative temps at idle. They can be dangerous howerver, YOU HAVE BEEN WARNED
The thing about Peltiers is, they produce ALOT of heat and you need some good cooling to get rid of it. Water cooling is about the best for doing this. Some people get good results air cooling them but I suspect their HSF's are about at their limit of effectiveness.