Hmm, probably true that they don't figure the case fans to use as much power. Good point.
The PWM fans I saw that were 180mm are made by Phobya. They may cool as well, which makes the second option more attractive, using the Sunbeam device with it's PWM to voltage converter.
As added to my previous message, I don't understand what Sunbeamtech Rheosmart knobs do: at first glance, if the mobo PWM signal control the fans connected to it, then those knobs look like pointless, while if they are not pointless, then the Rheosmart shouldn't be able to use the mobo PWM signal.
Maybe they should be used only without the PWM signal coming from the mobo header? At any rate, as said from other people, the PWM signal on Gigabyte boards is not the best one to drive down a fan, and with 180mm fans you have to go very low.
I cannot help with Phobya large fans.
Ok, these little devices are actually kind of neat. They have two modes, a knob mode, and a button below each knob that when pressed turns off that knob completely, which is the mode I would use them in, and turns on the PWM mode. In PWM mode, it uses a signal from the CPU Fan header to determine the fan output voltage, so 3 pin fans will spin down as if they were PWM. In this mode, the knobs cease to serve any purpose... hence my idea to mount the whole thing somewhere inside the case out of sight, seeing as I'd never be using the knobs.
Here's a link to the Phobya fan, that works as a PWM fan.http://www.frozencpu.com/products/16104 ... 79123.html