I've recently bought the i7 2600, My previous chip was a Core 2 Duo e8400, and i noticed with both chips, in all cpu temp programs i can find, the wattage jumps significantly. 9.8w under idle, ~45w under heavy load, and it jumps around alot very quickly. I understand why the wattage difference, but my question is if the frequency of the voltage changes (which is every second) could lower the life expectancy of my CPU's..
The changing of the Vcc for the CPU will not hurt its life at all, it will actually extend it since lower voltages reduce wear and tear on silicon devices.
While it seems like the voltage is changing quickly understand that the frequency of your CPU is the rate at which transistors in it turn on and off so there are portions of your CPU that are having their voltage get changed a few billion times a second, adjusting Vcc even 5 times a second is nothing comparatively.