Don’t forget the practical ability to dissipate waste heat on top of producing energy. That’s an upper limit to all energy use unless we decide boiling ourselves is fine, or find a way to successfully ignore thermodynamics, as you say.
If we'd ever get so far that would be the most compelling argument for datacenters in space
Heat rejection is far more challenging in vacuum.
We can always build a sunshade in the Earth-Sun L1. Make it a Sun facing PV panel pointing radiators away from us and we can power a lot of compute there (useful life might be limited, but compute modules can be recycled and replaced, and nothing needs to be launched from Earth in this case).