So it turns out that if a transistor is kept on continuously its threshold voltage gradually increases (Negative-Bias Temperature-Instability (NBTI)), increasing the switching delay. This attack targets transistors along the critical path, increasing the path's delay until it exceeds the allowed tolerance (guardband). Turning the transistor off "heals" it; as a workaround they suggest periodically executing certain nop instructions to ensure critical path transistors spend at least 0.05% of their time turned off. They perform simulations using models of 45nm high-k PMOS transistors to produce their results. A good quote about processor reliability:

   Guardbanding  is  the  current  industrial  practice  to  cope  with  transistor  aging  and
   voltage droops [Agarwal et al. 2007]. It entails slowing down the clock frequency (i.e.,
   adding timing margin during design) based on the worst degradation the transistors
   might experience during their lifetime. The guardbands ensure that enough current
   passes through the processor to keep it above the threshold voltage and in turn ensure
   that the processor functionality is intact for an average period of 5 to 7 years [Tiwari
   and Torrellas 2008]. However, inserting wide guardbands degrades performance and
   increases energy consumption. Hence, processor design companies usually have small
   guardbands, typically 10% [Agarwal et al. 2007]. However, the MAGIC-based attack
   can deteriorate the critical path by 11% and cause erroneous results in 1 month.

[1] https://www.researchgate.net/profile/Naghmeh_Karimi/publicat...

Probably decreasing, and soon not much longer than warranty period... the transistors have gotten so small that they're on the threshold of barely working even in normal operation.

As for older CPUs, they could definitely last many decades because of the lower stresses of larger process sizes, and they were designed with much higher margins.

Back when a certain kind of line printer was commonplace (has a circulating ribbon with the typeface repeated, and n hammers in a line going across the entire width) programmers could sabotage the printer by printing the pattern on the ribbon. This would cause all of the hammers to fire at once, which the machine wasn't designed to withstand.

I've also heard of monitors being broken by having the speaker output the resonant frequency of the glass cover. However, I can't vouch for this one.

You could also damage a floppy drive making it read/write, for many times, few sectors outer the common limits. Being there, done that.

But after so many discussions on online forums that it was impossible to cause physical damage using software (other than overwriting firmwares), I gave up and kept this (and the asm code) deep inside my heart.

And bringing it up still gives me chills that those discussions will return right now...

It's so long that probably nobody bothers to measure it.

    > Back in the bad old days of Linux, you could
    > easily damage your monitor with the wrong
    > xorg.conf settings.