Asus anti-surge has been know to cause issues. I'd recommend disabling it.

Update for those who care

What caused the buzzing? There was EMI noise on power outlet. I found out about this after having those buzzing show up on my microphone. In fact, the buzzing was there on my laptop with external mic as well. After disconnecting the laptop from any external sources like charger, external HDMI screen and ethernet, the buzzing was gone. (Yes, the buzzing can even get carried over just by having external screen plugged into my laptop.)

Did the buzzing killed me PSU? No. Definitely not. Other similar EVGA PSUs that are used inside my house have been functioning properly for months.

What was the problem with the PSU? The 3.3V rail outputting 3.67V. Now that alone would not cause it to shut down after it powers on. But I discovered that the voltage peeks above 3.8V when the unit it powered on then it lowers to 3.67V. Peeking the voltage to 3.8V or above will cause the WT7527 IC to shut the power supply down.

How did I fixed it? Thanks for EVGA for providing all the necessary schematics, I managed to track down what caused this to happen and applied a correct fix. This is obviously a joke. Like HELL they would make it that easy.

What did I actually do to make it work? The power supply has a brown wire, that's used to sense a voltage drop on a 3.3V rail on the 24-pin ATX connector. When PSU IC senses that voltage is lower than it should be on a 3.3V rail, it will provide slightly higher voltage to compensate. By simply connecting the brown wire to higher voltage than 3.3V, 5V rail to be exact, it had an offset effect. By doing that, the voltage on 3.3V rail went down from 3.67V to 3.48V. Doing this no longer caused the power supply to shut down under intended use. I tested the PSU for 2 weeks and it worked fine while being jerry-rigged.

I definitely spent a lot of time figuring it out. In fact, so much time that if I lived in a rich country and got paid the minimum wage of $8, and have actually used that time on a job, I could have afforded a new Tier 1, 850 W, Corsair PSU. What can I say? Life isn't making it easy and nether EVGA and their warranty policy in EU. (and their quality control on low end products)

After that, I decided to give the PSU away to my friend (who is still saving up to build a PC), because at least this PSU will make him happy.