Alright here it goes:
1. Open up rivatuner > Power user
2. Scroll down to Rivatuner \ Fan
3. Change the value of AutoFanSpeedControl to "3" (this enables you to change the settings if you wish), exit and reopen rivatuner
4. Go back to the Main tab
5. Click on the customize button in the "Target adapter" box
6. A little menu will pop out, click the first option (looks like a video card) named "low level system tweaks"
7. Click on the Fan tab (should be default anyway) and check mark "enable low level fan control" and click on "auto"
here is what the values mean:
Duty Cycle min = minimum fan speed (in %)
Duty Cycle max = maximum fan speed (in %)
Tmin = minimum operating temp (if the GPU core temp is below this threshold, the fan will spin at the min duty cycle you assigned it -- make this number reasonable)
Trange = Controls the relationship between the fan speed and core temp once it surpasses Tmin (I'll explain this in a second)
Toperating / Tlow limit / Thigh limit = automatic system fan control (I'll explain this in a second as well)
First things first:
Set Toperating = 110, Tlow limit = 0, and Thigh limit = 110. By doing this, we will be able to control the automatic fan without having the system butt in by itself.
Next set your min fan speed to whatever you would like (I set mine to where I can just barely not hear the fan ~50%) and set the max fan speed to 100.
For Tmin, it is up to the user to decide. I personally chose 55 as the core won't get above 55C unless it's in some kind of crazy 3d usage. This way, I keep the noise to a minimum and she stays nice and cooler at idle / low usage.
As for Trange we must calculate this number:
Trange = (2*3) * {Tmax-Tmin)/[(Max Duty Cycle - Min Duty Cycle)/100]}
For this equation you must decide what your Tmax will be (basically the number at which you want your processor to run at). Once again select a realistic number. I found that this temperature will make your fans run about 80% or so. The lower the number, the faster then fans will increase in speed, the higher the number the more heat it will take to speed them up. Usually your number will be between 20-40 depending on how much fan you want.
Also note Trange must be an integer number and the number you put in might change automatically. Apparently the system can only accept certain numbers so it'll round to an acceptable one (for example I input 25 and it changes it to 26) so don't be alarmed by this.
Once you input your settings check apply at start up and I believe you have to have rivatuner start at start up as well (though I'm not sure about that).
Hopefully you got all that
Here are my settings:
Duty Cycle min = 50
Duty Cycle max = 100
Tmin = 55
Trange = 20
Toperating = 110
Tlow limit = 0
Thigh limit = 110
By doing that my OC'd GTX stays about 73C @ 80% fans on furmark which is about as intensive as you can get. F@H yeilds about 62ishC core temp and 60% fans so barely audiable