The effects of electrostatic migration are not transitory in systems that are running 24/7. Simply restarting the system, or turning it off for a few hours will not lessen the effects. The effects are cumulative. Electrostatic discharge is the characteristic (affect) and electrostatic migration is the effect. Given a system running 24/7 with highly volted CMOS substrates to the point of highly cumulative electrostatic discharge will bring forth the effect of electrostatic migration in the longer term and this is what permanently damages the CPU.

The characteristic (affect) will lessen in time, however the effect will not. Since the effect is cumulative, there WILL (in time) be a lessening of processor validity in data streaming and more adverse effects on the silicon. Very highly overvolted CMOS substrates will find the effect far more quickly than those who moderately operate the voltages.

You will see the effect before the affect. In other words, if you run a highly volted CMOS substrate you will see issues result. The system runs fine for days and then for some strange reason, it reboots. The games run fine and then for some strange reason (without software or hardware change) the FPS lower, etc. You shut your system down for a day or two and when you start it back up, it runs smoother and faster FPS etc. There are many more effects but I am sure this is clear.

Regarding life expectancies of the highly volted silicon substrate? One cannot, with any certainty gauge the life of such parts. Silicon Substrates do not have a life such as humans and animals etc. have. In their physical nature (with regards to electrostatic discharge and many other atomic level migrations) they are endowed with a half life, so you can consider their span as radioactive decay for purposes of determining possible length of minimal error use.

For example:

Given:

10,000 New CMOS's from the same fabrication silicon wafer. Their half life is the time that would pass before 5,000 of them fail. So, based on how long people have working CMOS's of the same fabrication silicon wafer, the half life of your CMOS could easily be 10 or more years (non overclocked).

This is why maximal voltages are given by the manufacturer. Be clear that the above does not mean that you will damage the CMOS in the shorter term. The problem is that one can not differentiate which is the silicon substrate that will last the long term and the one that will not. Highly overvolt the one that will and you very likely will still have the CPU for longer than you will want it but then you have the ones that are on the short end of the standard deviation (short end of the stick if you will) and the high overvolt will return errors and finally issue more frequent hardware interrupts.

It's the luck of the draw