It is not loud at all. It runs on a 120mm fan and not the 80mm fans you will find in most PSU's and IIRC the tagan uses an 80mm fan. Small fan = higher rpm for same airflow as large fan/lower rpm. It is also thermally controlled so will adjust to the heat of the power supply. I have one, and built one for my friend and they are not loud. Yes, the seasonics are quieter, but they are really renowned for silence (and designed for it).
EDIT: I referred to the wrong Tagan, as the 430W one has a 120mm fan.