TurtlePerson2 wrote:The part of the processor that breaks is not the transistors. The integrated circuit elements are not destroyed by 3 volts. A few hundred volts might destroy a gate oxide, but a minor change in voltage shouldn't cause any transistor problems.
Partially correct -- a high voltage is what it would take to punch through a gate oxide instantaneously. Which is why we use ESD precautions.
However there are more gradual mechanisms at work. Back in the old days, everyone in the overclocking community used to know a thing or two about
electromigration, in which the semiconductor doping compounds can gradually be moved between two regions of potential (voltage) difference until a kind of short-circuit path is created. A lesser-known problem in MOSFET devices is
hot carrier injection, in which charge carriers having sufficient energy can tunnel out of the silicon and become trapped in a FET's gate oxide, increasing the
leakage current. Both of these phenomena are aggravated by increases in operating temperature and operating voltage. Over time, the silicon device's stable switching frequency may be reduced, and its operating current and therefore its heat dissipation may increase.
I don't know how much of a problem this is on modern devices, especially given the complex power and clock management technologies that prevent the user from doing whatever they want. In the old days, the chip simply had to accept whatever input voltage and clock it was given, and either it worked at those parameters, or it didn't. Or in the case of a K6-2/400 I experimented on, it worked at 504MHz for a while but became increasingly unstable, and then it wasn't stable at 450MHz, and then it wasn't stable at 400MHz. Then it sat in a workbench drawer two years, and when I gave it to a relative with fair warning, it started working at 400MHz again, and did so for a couple more years. Go figure.