Unless the mechanical clutch fan is radically different on an e46 than and e36, it would never really "turn off". It maintains a constant grip. In your case, it's too tight, spinning with the engine rpms. I don't think you can hear it past 40km/h because of the wind noise...
1998 BMW 328is - summer
1994 BMW 325i - daily
1992 BMW 325i - gone
1988 Mercedes Benz 190E 2.3-8V - sold