It's quiet as far as I've noticed, actually thought it was quieter than the 980ti it was replacing. I've had it in two cases an Air 240 and now a Node 202. In the node at least my CPU is way, way louder so it drowns it out regardless of how loud/quiet you might perceive it to be. It's certainly not blower style loud.
Oh by the by in terms of performance I found it to be just a few FPS slower than my 980ti, which was one of the higher end models. So it's a good bang for your buck, especially if you need a short card length.