this is already done. about a quarter of the big panels on the International Space Station are radiator panels.

they're always aligned 90° away from the solar panels so the sunlight hits them edge-on and their faces are pointed towards empty space.

a satellite with data-center level servers on board would need an absurd amount of both solar panels and radiator panels, so many panels that it would need to orbit much higher than the ISS, because of trace atmospheric drag.