Those fans will actually run OK at 6-12 V if you want it quietier. You can source some appripriately sized resistors to drop the voltage at the desired fan current.

Or you can use these little guys: http://www.ebay.com/itm/ZALMAN-FAN-MATE-2-VAR … =item3a6b37d3ff

just search for zalman fanmate. I have like 3-4 of them around teh house because I use their heatsinks often. But they make perfect little speed controllers.

I'm still just running it off the 5V rail of the PS and it's doing OK. I did add an intake fan, though, since to make things a little better. Might further add a duct from the intake fan to the CPU heatsink just for a little extra cooling.

Nice little gadget luckybob! It sure makes things convenient, but at ~$9/ea w/shipping to Canada, its too expensive for me. A resistor and some solder would be about $0.15 to slow down the fan.

If I bought one of those, I'd want to buy one for every computer I have running. I'd be looking at $100! I hate noisy computers.

If your computer fan is getting old, or loud, you'd probably need to replace the fan anyway. New fans can be noisy as well, but most manufacturers have different ranges of RPMs for the same fan series at, say, 12 V. Sunon is a good example of a company with several RPM speeds per single volt fan series.