"but surely something can be done by putting computing power outside the life supported areas."
Think of it this way. Space is a very near vacuum. The *entire* structure is inside a vacuum flask.
If you want to dump heat you can do it by conduction, convection or radiation.
Conduction. Nowhere to go.
Convection. No fluid *outside* the structure to convect.
Leaving radiation. Hence the rather large flat structures that aim to dump waste heat into the shadow of the station.
Mine would be the college physics textbook in the pocket.