I understand. It's pretty common for people to reuse the PSU from an older build though, which is why I asked.
So in light of that, I think I'd be talking to Corsair's RMA technical support. Explain the situation in detail regarding the clicking and the buzzing. I've installed a few RM units for people and none of them buzzed or had other than minor clicking when the fans kicked on or off. Explain to them that this is different, exactly as you've explained here. They may say it's normal, but at least there will be a record of it if something gets worse later, and they may just say to send the unit back to the retailer.
You can probably also contact the retailer, maybe do that first, and try getting a replacement through them.
Whatever it is, it's not something you're going to fix if it's internal to the PSU. I'd definitely check around in the case though to make sure it isn't something else, first.