Strange buzzing sound

[nitroxc]

Took my headset off while gaming and noticed a buzzing sound.

Really unsure where it is coming from and was wondering if you guys could help figure out what it is.

Specs:
Xeon X5650 OC'd 4.4ghz
Asus P6T deluxe (latest bios)
2x4gb Corsair vengeance LPX 1600mhz ddr3
inno3d X2 gtx 1080
1tb HDD
525gb ssd
Corsair H110 (Nanoxia 140mm low noise fans)
Corsair CX600 PSU

[video="https://www.youtube.com/watch?v=UwyEcRF-0Zs&feature=youtu.be"][/video]

It's fairly loud but i dont really know where to start.

 

[Sedivy]

Sounds like a front fan on the radiator but it gets strangely louder when you move to the bottom of the case. Not sure...
You can just sit your radiator out on the bench next to the computer (if the tubing is long enough) and that might make it easier to check if that's it?