Yeah it is a tad on the loud side when under full load. However, after speaking with someone that uses one 24/7 - it remains really quiet for them in their Conroe rig. Its just when you push past 35a on the 12v rail that it starts to pipe up the noise a bit.
IMO they could have chosen a better fan (41dba @ 12v is a bit loud), but they did a good job of keeping it quiet in most situations.