Since Helium has a boiling point of -268.6C and a melting point of -272C, it would be the best element to use to cool the CPU. Since -273C is Absolute Zero, I don't think you will have to worry about solid helium in your cooling system. All you need is a powerful compressor and a powerful cooler for that compressor.
I would love to have a Liquid Helium Cooled CPU.
If only if Asetek would make one.
