Leave it idle. For every thousand dollars of energy extra used you will earn one cent worth of bitcoin and the denomination of bitcoin will be so small you wont be able to spend it. Regular computer mining bitcoin died a long time ago. Leave it alone.
Why not use these computational power for computations of BOINC projects? Rosetta@home, Test4Theory@home etc...
I am hoping/wanting to put them to good use but also recover some costs. That said, I don't yet know what I will do, just looking for ideas which is why I thought I would post since everyone here is knowledgeable.
The point is that I am already paying for these costs so am looking for something interesting, profitable to some extent. I am not looking for a get rich quick scheme nor do I believe in overnight riches. Just makes sense to look.