Just received a BFG TECH 550LS power supply. It has 550 watts and Active PFC. Is it normal for a PSU with ACTIVE PFC/Thermal control to have a 4-5 second lag from power up before the FAN starts working? And if I power it off the FAN still spins for a few seconds too. The BFG PSU is not really quiet, it has a low humming sound. Also the first time I turned the unit on - there was this weird buzzing sound that seems like the FAN is having a hard time spinning (it worked after a 3-4 seconds). Is this a defective unit? or is the auto temp control for the fan causing this?