With a rated output of 12.1 Volts and 37.2 Amps, we're looking at a 450 Watt power supply. The power supply has no dedicated cooling, and relies on the main system fan to keep cool—allowing the Mac Pro to idle at a whisper-quiet 12 dBA.

For comparison, we found a 450 Watt PSU in our recent Steam Machine teardown. The Steam Machine's SilverStone power supply featured a "silent running 80 mm fan with 18 dBA minimum."

And a quick look at what's left on the behemoth of a heat sink: Heavy gauge, flat power cables run from the PSU to the logic board and graphics cards, and remain intertwined in the heat sink.