zlacker

You’re correct that Stefan-Boltzmann uses absolute temperature (K), but that only reinforces the advantage of moving the "hot side" of the gradient up. If you increase your radiator temp from 300K (standard Earth ambient) to 360K (hot silicon), your radiative efficiency doesn't just go up by 20%—it nearly doubles.

The Solar Load is Directional: Unlike a terrestrial atmosphere where heat is omnidirectional, space allows for "shadow engineering." A simple multi-layer insulation (MLI) sunshield can reduce solar flux by orders of magnitude. We do this for the James Webb Space Telescope to keep instruments at 7K while the sun-facing side is at 380K. For a data center, you don't need 7K; you just need to keep the "dark side" radiators in the shade.