Why does my audio interface buzz? (No seriously)

Read below for more details or skip to the end for TL;DR.

I have an incessant buzz problem. You might be thinking "it could be the cable". Well no, it's not. No cable I use gets rid of the buzz. I have tried 3 or more different cables and even a brand new $60 Runway Audio cable.

Okay well is it the interface? No, I bought a brand new interface just to test this potential issue and it still has a buzz. I returned it.

Okay well it has to be my guitar then right? Nope, the buzz is there on both my guitars and my bass, and when I use a mic. Cool.

Okay so it's got to be your device, yeah? Nope. The buzz happens on my shitty laptop AND my brand new PC I built specifically for music.

Is it the location I'm recording in? I don't know, I've tried in my room, my kitchen, and even a relative's house. The buzz remains.

I legit don't know what's happening. As far as I know, my DAW (FL) is running just fine and the sample rate matches my computer and the ASIO. Do any musical detectives have any idea what the f*ck could possibly be causing this buzz? It makes it very hard to create professional music.

Tl;dr: I have a buzz that persists when recording, no matter what interface, cable, instrument, computer, DAW or location is in use. Any ideas?