[gcthomas]

The most important problem with keeping old computers running is their carbon footprint. Modern machines are much cheaper to run for the same performance, and even considering the construction of new devices an always on devices needs to be modern and lower power. I've replaced an old Asus nettop PC with a Raspberry Pi 4, and electricity usage has dropped from 30W to single digit power consumption.

Old devices need retiring, like old cars.

[NoGravitas]

On the other hand, I saw some research that says that the power consumption of those older devices in use is dwarfed by the power used to make them, or to make a newer computer, so, as with cars, the right thing to do is keep them running as long as you can. I spent a little bit of time looking for the reference, but it was on gopher a couple of years ago, and I wasn't able to find it.

[detaro]

On an individual level there's another angle: Wait to long and you run into the point where other people are scrapping newer, more efficient machines. At that point, picking one of those up is increasing your efficiency.

[c22]

But as with old cars, if you want to keep one running you might need to learn some more about how engines work. Or be willing to pay a mechanic.