In addition to the math, you can also look at existing examples, like how large the ISS radiators need to be relative to its solar panels. Like this project, it is essentially a closed system where all power generated by the solar panels will eventually be converted to heat that needs to be dissipated.

I'm skeptical that it makes any economic sense to put a datacenter in orbit, but the focus on the radiators in the last discussion was odd - if you can make the power generation work, you can make the heat dissipation work.