@thelastpsion The sad fact of the matter is that most old computers should not be repurposed, because newer devices are available that are vastly more efficient uses of electricity.
A Raspberry Pi 5, for instance, is more powerful than a lot of older computers, but consumes a small fraction of the power.
The amount of electricity I would save in a single year of running a Pi 5 compared to most older machines of similar capability would pay for the Pi 5.