processors are are built with a lifespan of about 20 years.
they are also develloped to work @ a voltage, and if you look at the processing method (45nm ... etc.) the smaller it is, the lower the voltage is. all that because the smaller the cpu are made, the transistor are smaller and the distance between those is also smaller.
in every cpu there is electron migration and thats normal. but if the vcore is increase by a good margin then you will accelerate the electron migration and you cpu will die faster.
in order to stay with a good lifespan of your cpu, keep the temps and the volt the lowest possible
heres the explaination of eclectron migration
Electromigration - Wikipedia, the free encyclopedia