I’ll just come out and say it: 50W. I know, I know an order of magnitude above what’s actually needed to host websites, media center and image gallery.
But it is a computer I had on-hand and which would be turned on a quarter of the day anyway. And these 50W also warm my home, although this is less efficient than the heat pump, of course.
What’s your usage? What do you host?
My setup already goes quite a bit beyond basic file hosting.
There is no self hosted service I could imagine to need that I’d expect not to be able to host due to CPU constraints. I think I’ll run into RAM constraints first; it’s already at 3GiB after boot.