im
using one of these fans to suck cool outside air thur my rad (
a DDen heater core). they have specs comparable to panaflos (they're in between the medium and high-speed 120mm panaflos). with two of them on at 12 volts, they are relatively quiet. you can hear them of course, but they arent annoying at all. with them running at 7 volts, they are exrememly quiet (you can still hear them if you have a good ear). my hdds are louder than these fans @ 7v lol.