Buzzing noise from computer help

[Pokesaurus]

My computer for the past few months has started buzzing at what seems to be random. I don't know what is causing it and I don't know which part. I've tried looking up videos to compare sounds but I haven't heard anything like it. Sound is below:
https://youtu.be/okm4MYdQTCM

 

[elbert]

Try the disconnect method. Unplug drives, video card, and fans one at a time till you find the problem. Not the heatsink fan just a fyi. Once you get all those done then move on to the hear test. For any devices you just cant unplug and would keep they system from run of course.

 

[Dunlop0078]

Sounds like a fan touching something, or maybe a dying hard drive. To me It does not sound electrical and its definitely not coil whine.