What do you run your fan at 5v? What does it sound like at 12v? I might hook a fanmate to it and set it to 6-9v (whatever my noise threshold is).
Basically, the fan comes with 4 3-pin connectors. 2 run at 5v, the other at 12. The fan is quite audible at 12v. I currently have four fans plugged into my multi-fan controller, and I need to redo some of my fan hookups (i.e.- Make/buy some extension cables for my 120mm fans so I can run them into the switches on the MFC, since I only run them at 5v anyway).
The nice thing about the extra fan plugins for the Zalman fan is that I can plug in a nearby Panaflo into the other 5v connector.
Anyway, once I have room on my MFC, I'll probably play around with slowly increasing the power to the Zalman fan till I can get maximum airflow at minimum/no noise.