Humming Sound After Replacing PSU

I was having an issue a few months ago where my PC would randomly power off during games, so I replaced my old PSU with a NZXT 1200W 80+ Plat supply. However, since replacing it, I started hearing a humming sound coming from my PC. It doesn't sound like fan noise and the sound is very clean and similar to a dial tone you'd hear on an old phone. The sound doesn't really change in pitch much, and goes for up to 30-ish minutes at a time. PC load/temps don't seem to affect when it starts happening, nor how long the my computer has been on for. It's been happening on and off for the 6 months that I've been using the PSU, but I haven't had any other issues with it. I'll see if I can record it, but it sounds identical to a ~240Hz sine wave tone.

Has anyone else experienced this with a power supply? I can't find anything on google that isn't about bad fans.