H110i GT high-pitch whirring sound

[NS_frostbite]

Hi all, i built a new pc yesterday with a H110i GT mounted on the roof of my H440 case. However the fan(s) are making a whirring noise, not a constant hum, but kind of a pulsating sound. It gets worse at mid to high RPMs, but is always audible and very annoying.

Here is a clip of what it sounds like and an image of my PC:

Sound http://vocaroo.com/i/s12sUqtatmGa

Image 1 http://s17.postimg.org/687awvnjj/20160117_021607.jpg
Image 2 http://s18.postimg.org/iq5zk3ud5/20160118_165300.jpg

The top radiator isn't mounted using all screw points as it simply wouldn't fit. It's held on by 4 screws, but its still very sturdy. The actual source of the noise seems to be coming from the left fan (the one closer to the rear of the case). Any suggestions to what could be causing this & how to fix? Thanks

 

[maugusto]

if the fan is very noisy you can RMA the entire cooler (fans and the rest of the cooler can't be RMA independently) or you can put some nice fans silent fans like Noctua NF-A14.
I have one H110 and the fans ave revy noisy (cheap fans they put in the good coolers) and then i put 2x Noctua, result -> Silence