Does a CPU keep its processing speed after years of use? Is electron migration an issue that affects CPUs? [duplicate]

Solution 1:

CPUs will not change speed with age. Their speed is determined by the clock speed and the physical design characteristics of the CPU.

CPUs do seem to get slower over time. This is caused by a variety of factors, but the main is simply that the things we use CPUs for is changing. For example, you might think you're just using your computer for the same "email and browsing" that you used to do. But email and browsing today are nothing like they used to be. For example, if you compare web pages today with web pages five years ago, they are completely different things.

Solution 2:

Actually, CPUs and electronics components in general do age with time. It might happen that this aging phenomenon impacts the maximum clock speed of the CPU, but assessing the impact on a real case scenario would be next to impossible.

The main problem I see is electromigration. Basically, on the CPU you have tons of transistors connected by very short and thin metal traces. The electrons, when moving in the conductor (Al or Cu normally), can punch some of the lattice atoms. With time, the atom moves around and settle in places where they are not supposed to be. This phenomenon is similar to what happens with a river, that slowly transports materials from one place to another.

Electromigration can destroy a connection, and this would lead to a non functioning CPU, but before destruction, the connection gets thinner and thinner, so the series resistance increases. If the connection is the power supply for a certain block, increasing its resistance means that the voltage the block will see, will decrease. Roughly, less voltage = less speed, so you might get unreliable operation because of race condition between paths that now have different speed because of aging. This problem can be solved by reducing the clock speed. The actual clock frequency is not impacted by electromigration, because the clock is generated using a quartz crystal, which is extremely stable in any scenario.

This phenomenon is well known and studied, and it is taken in account when designing a chip. I do not expect any modern consumer processor to have such a problem, within its designed lifespan at least, but the possibility is there.