@mian
I just have no idea just how much does it need to change.

It doesn't have to pay itself, it doesn't even need to stay even. It just has to cover the difference between running it from running a heater directly.

@LukeAlmighty I wonder if you can scavenge e-waste for mining. Like buying lots if shitty old office computers to do it.

@mian
I guess the true problem is the exponential power of computing.

So, unless I pay off 1/2 of the total cost in the first year, 1/4 the 2nd... it won't be good enough. And I guess that anything not modern really won't do.