AS noise is subjective
 
I tried to compare my Hybrid radiator fan to the GPU "blower" fan inside the card

 EVGA GeForce GTX 1080 Ti FTW3 HYBRID GAMING, 11G-P4-6698-KR
 
At 3 feet, open test bench - I can hear that the fans are running --> They are Not Loud or Noisy


 
 

 
On my Open test bench: (my ear about 6 inches away from fans)
 
My "blower" fan inside the GPU @ 58% - 60% speed according to OCX and the level of sound at the radiator is about the same or even less - and a different pitch, lower tone than the blower fan.  I think the blower fan is noisier and has a more objectionable higher pitch sound
 
(Unscientific test - but better than my ears)  Stock fans, open case / test bench
 
AT about 2 inches with Radio Shack Digital sound level meter 33-2055
( 2 inches very close to point sound meter at fan, may be causing results to be off - wanted to zero in on that fan & not background)
 
Room 57 dB C at 6.5 feet elevation (trying to avoid PC noise in the room)
 
GPU blower fan 60% = 80 dB C
 
stock EVGA Radiator Fan / push - through the radiator = 73 dB C
 
stock EVGA Radiator Fan / push - measured from behind/ before the radiator = 76 dB C
 
Corsair AIO CPU cooler H110i 280mm  (not sure of the RPM right now no software to monitor at this time)
 
stock fans /push through the radiator = 67 dB C
 
measured from behind/ before the radiator = 75 dB C
 

This is what the GPU were doing during the Sound Testing
 
Running nonstop last several days -->  Heavy load GPU - Folding @ Home project
 
Room 25 C
 
GPU 1 = 43 C / 82 % GPU usage
 
GPU 2 = 46 C / 92% GPU usage
 
    *GPU Temps based on EVGA Precision 6.1.14
    *Room Temp based on portable digital thermometer "Acu-Rite" model 00380

There are other PCs in same room -- room has background noise
 
The 24 inch portable box  fan across the room makes more noise - turned Off for dB testing
 
The FTW3 Hybrid radiator fan speed is controlled by the GPU - stock, which is the way I'm running mine.
 
Note:  If you move the rad fans to a different controller and force a higher RPM - I'm sure you'll probably get increased sound "noise"
 
 
*** OK, now when you post your comments --PLEASE -- share your testing ***try and make this objective not subjective 
 
Sound : before /after & how tested

 
Temps: before /after & how tested (stable GPU load required to test Temps)
 
Fan Setup:
 
      Brand, model & RPM

 
      Connected to GPU, MB or other
 
      How do you control fan speed
 
 
 

I thought all those members that switched their stock radiator fans would surely want to share their experience in this thread

Cool, I use a Corsair pressure optimized fan, SP120. I couldn't give you noise levels.. I haven't been home most of the time since I booted it.

Different fans don't change much, rpm control does.

I think I posted awhile back I'm using a Sythe GT AP-14 at 100% off the motherboard. It's quieter than either of my hard drives. Quite a bit less noisy than the stock fan.