i dont know how you plan to hook this up,,,,-110 would freeze any water it might be put near, and would damage and chip it is put on. To overclock a 3ghz machine to 6ghz would damn near instantly fry the chip without the cooling, however, if the cooling is started before the chip is overclocked, the chip is then destroyed by being too cold, well not so much destroyed but significantly damaged. You would need a thick insulator to hold your coolant system, which would take up space in a tower which usually doesnt have much space.
Your radioactive material idea will never work, as no one will sell you radioactive material to put into personal computers. Your design is too dangerous and if there happens to be a leak it would ruin the computer it is in, or worse silently leak CO and kill the people in the house. Nothing is full proof and if u live in the US you better be ready for people to screw up your design and sue you.
Thats the optimist's view...lol