Comment What's old is new again/using wasted space (Score 2) 61
When I demoted my single Pentium 4 rig to workshop use
it noticeably raised winter temperature inside my
sealed 40ft High Cube shipping container machine shop.
It's not difficult to rack or shelve many computers near the ceiling or hang them off walls. I hang a 1U server off the wall of my office as one would a painting (and could cover it with a painting if I cared). Total cost is a couple of small lag hooks costing less than a dollar.
I don't do mini/tiny PCs for space reasons because there is more than enough unused space in most rooms to make that unnecessary, and for access a computer on the wall is hard to beat. Needing no desk my server doesn't clutter mine.
If I wanted mining rigs I could line walls with them high enough not to interfere with anything else with heating as a bonus.