I heard at a HPC presentation that the fan in the power supply of a 1U server
"pizza box" can draw 15-20 W! I looked up the specs of some 40 mm case fans used
to cool CPU, DIMMs etc and they were in the range 4 W to 13 W. So I suppose
15 W is plausible.
On the other hand, the larger case fans in a desktop PC need only 1 to 2 W.
So would it be reasonable to assume that in a desktop power supply, the fan
is roughly 2 W draw also?