I have heard that the Zalman without it's controller always runs at 100% fan speed.
I have mine turned all the way up and I don't think it's very loud at all.
Then again I have an ATI HD4870 sitting next to it with the fan at 55%. The Radeon is the loudest component in my machine by far.
- Witt
PS - In a couple weeks I'm putting in a second one too... lol