Heat from the power supply system is not relevant. Heat on
individual components (that should have heatsinks) may be excessive.
Surface temperature of major transistors and diodes should be
measured. But again, those part surfaces may be many hundreds of
volts. Temperature of case is not relevant. Temperature of major
internal parts is relevant. You cannot safely touch them with a hand
or conductive temperature probe. But if a part is exceeding maybe
150 or 180 degrees F, then consider installing a heatsink on that
part.

On Jan 27, 7:30 pm, wrote:
Just to let everyone know, after monitoring the temperature of the the
PSU and the air emanating from it, and seeing that they were booth
essentially room temperature, I removed the fan (realizing the safety
implications astutely pointed out by w_tom).

The PSU is a /little/ warm to touch now, but there's very little heat
actually radiating from it, and it's still completly comfortable to
hold. It's been on and powering the device for over a week now, so I
think it'll continue to be fine.