Question My PC makes a buzzing noise every time I turn it on, which eventually gets quieter until it stops.

[Un Chungus Muy Largo]

My PC has a problem where whenever I turn it on, it makes a buzzing noise. This buzzing noise gets gradually louder, then quieter, until it eventually stops. This happens over the course of about half an hour. What's interesting to note is that tilting the case a small bit quietens the noise, and sometimes makes it stop altogether. I have a Zalman Z11 Plus case, an MSI GTX 970, an i7 4790K, a Gigabyte Z97X Gaming 3 motherboard, 16GB of HyperX DDR3 RAM and an EVGA Supernova PSU. If anyone knows what could be wrong and has any solutions, I would like to know

 

[OvErKiLLzZz]

Any luck? I started having the exact same problem, the temporary solution i have is to grab the front of the computer, lift it and smash it down.
The sound seems to be coming from the back of case, what im assuming is the psu.