Software Coolers

Are there any software coolers that can be used for XP?
I used ot use some like Rain for 98, but none work for XP. What these programs sued to do was send signals to something on the motherboard that would shutdown certain circuits or whatnot that were not being used and it would help keep the board from using any extra energy. Know what I mean?
If so, are there any out there you know of?