There's also a small amount of wear simply from the drag of electrons running through the fine filament threads of wire they are piped through. The longer this

There's also a small amount of wear simply from the drag of electrons running through the fine filament threads of wire they are piped through. The longer this goes on the more electron tunneling will happen, degrading the CPUs performance. We don't notice them on larger wires as the wear is infinitesimal, but in a CPU where the wire diameters are in the micron scale and below there is likely a maximum lifetime of usage before the whole system becomes inoperable. Might be 500 years of continual usage, might be 50, I don't know and I don't think anyone has done a long-term study on how long a CPU can be continuously operated before it fails, but the risk is there.