Kywim

I plan to try 0.5 or 0.75v and see how it goes, if I want it a little cooler I'll try lower, but I have a few questions:
When idling, my CPU's VCore goes down to 0.8v, with undervolting, it'll go even lower I guess? Will that still be stable with (e.g.) 0.7v? I don't want to crash at idle ? Are these the correct steps to undervolt my CPU? Go to the BIOS Find "VDDCR CPU Voltage" and change it from AUTO to OFFSET MODE Set the OFFSET MODE to "-" (minus) Set the OFFSET to 0.05 (or the value I wish to use) Will I need to change any other setting, such as "SoC" voltage? Sorry if theses questions seem stupid, but It's my first time changing BIOS settings like that I'd like to be sure of what I'm doing

The noise is random. I don't have any way of reproducing it for sure, so doing that is going to be hard
 
I think I'll try to play the rest of the day with the PSU dust filter removed and check if the noise still occurs. If it does come back I'll record it.

I think this is simply case vibrations. I removed the PSU filter, the noise came back but was less loud, and I applied some pressure with my hands below the psu and the noise completely stopped. How can I fix this?

It is a brand new one. I received it like 2 weeks ago. It was tested by EVGA before being sent and they were 100% sure it was fine.

I'll just keep it for a few weeks and RMA it I think, unless it's urgent I'll wait for the new one.

My last one had a very similar noise and lasted years