I suggest you get a Hydrocopper card and water cool it if you are that sensitive to noise....

Upgrading to two 780 classifieds from two 580 classifieds I can tell you that the noise level is wayyyy lower than the 580s. When I first raised the 780's fan speed to 100% I thought my precision was installed incorrectly or my fans were broken because they were so quiet.

They are quiet... too... quiet....

Even at 120% they are whisper quiet. (I overclocked the fans too)

 
Sure my 580 Classy is loud at 100% fan speed. Do I need it at 100% fan speed? The answer is of course, no! I let my Precision run my fan profile. It never gets hot enough to need 100% fan speed. 70%? Sure! My card doesn't get hotter than 72c in intense gaming. My next card will probably be the 780 Classy. Not because of any noise levels. Just because it's a faster, and newer card. That's why.          

Those who say its quiet must have a higher ambient noise level or somthing becouse i have a silent running case. its a Cm storm Stryker with stock fans on level 6 of 8 speed setting and a NH-D14 cooler which is silent even on max speed.
But
This 780 Clasified ...the air woosh noise from the fan is fine..but at 65% and above the noise of the fan motors resonating away/humming is easily audable at 2 meters away (which is where i sit), and not what i would call quiet.

My last card was a 560ti SOC from gigabyte. B4 that i had dual 8800GTX cards in a very noise Dell XPS 720 H2C rig. This was many years back though.
 
So whilst i undeerstand there are noisier cards out there ..this card boasted quietness and i dont consider it quiet by any stretch.

You would be surprised how many people think a 780 is overkill for 1080p and are infact wrong.
Rift for example at 1080p full settings including its SS option can run anywhere from 30 to 60 fps. And its not due to a engine or CPU bottleneck.
Also Crysis 3 at 1080p Ultra settings and AA, 1 780 isnt enough.
Metro another example.
There are plenty of games out there that if u put on max settings can and will max out a 780.
 
As for the fan curve iv done my best to keep things low but the GPU throttles at 80c no matter where i set the temp target so i need to keep it below 80c, that requirs up to 75% fan speed.
 
Thankfully, with the game sound going and my music, i cant here my rig till the GPU hit 90% fan speed which it never does.. its only when im benching in like 3dmark with no sound or when im playing just a game with no music and im in a quiet area that the noise becomes annoying.
 
Im running its stock settings atm so its boosting the voltage to 1.161mv on its own to get 1163mhz on the core.
If it gets on my nerves to much i may see if i can undervolt it, as when it throtles it goes down to 1150mhz and 1.135v.