The Pantser

Pooping is 3D Printing and your butthole is the extruder.

I would think actually more efficient because heat is the waste product not the expected product like a stand alone heater. Unless you are specifically running your PC at max just to create heat then just using your PC as intended and gaining “free” heat is a bonus.

My homelab is in the same space as my furnace so the ambient heat in that space is preheating my ducts. In the summer when the AC runs the cold air leaking into the space helps cool my homelab. In my garage office my desktop with 9 spinning drives and 3070 really keeps the space comfortable.