I have the 850 GS3. Not exact, but similar to the model you are asking about. Though some have suggested the fan profile for the 850 and upwards is a bit more aggressive than the lower wattage models.
When the fan turns on (if you have ECO mode on), it is quite noticeable. I am testing it with ECO turned off so that the fan is continuously blowing and probably maintaining a lower temperature, instead of suddenly blasting the fan to catch up when on ECO mode. I'll update as I observe more, since this is the first day I've got it on ECO OFF only.
If I had read the very recent G3 850w review on this site before my purchase, I probably would have gone for the Corsair RM750x or 850x, purely for the noise profile.