Unfortunately, the fan audibly be heard at idle (slightly rattling / booming), even though he comes from Enermax itself and the famous Twister Bearing has. Since I am still freak, I have expanded the fan and replaced by a very low current Pope-quality fan 12 cm. Between fan and power supply case I installed an additional sound-absorbing rubber mat (12cm opening). The lead of the Pope's fan I brought about the opening of the power supply cables and connected to the motherboard. "Idle" I set a speed of 500 rpm. Now there is perfect peace.
Opening the power supply housing is associated with a loss of guarantee (seal broken). It is positive that the Maxpro power supply will run even if you remove the 2-pin connector of the supplied fan. Otherwise it would not be operated with the Papst fan externally connected.
The Maxpro replaced my old Enermax Pro82 + (385 watts) in 2009, which is not completely compatible Haswell. The latter manifested itself in crashes when the BIOS the Haswell C6 waitstates (extreme power saving) were activated. With C3 the old power supply was stable. The Maxpro has not caused any crashes even if C6 is activated, what the full Haswell Compatibility confirmed. Tensions are idle with 12.38 volts, 5.20 volts and 3.42 volts slightly above the norm (determined with HWInfo 64).
With an external power meter can hardly measure the consumption of the upgraded with the Maxpro computer. The values jump "idle" continuously between zero, 30 and 60 Watt back and forth. With the old Enermax PSU consumption was shown constant and without these jumps. Presumably, this is due to the new technology (Haswell compatibility). The efficiency of the Maxpro should be at 87% according to the manufacturer - a very good value.
Incidentally me the fan was already talking about the old Enermax 82+ too loud. I had already at that time the abovementioned Pope fan velvet "Iso-mat" built into this. So he is now "migrated" from the old to the new Enermax PSU. Convinced had me at the old high Enermax quality (voltages stable, reliable long-term) and so on - features that so far has also Maxpro. With quieter fan the Maxpro me full five points would have received.