I’m not talking about dual booting but other Linux bootloaders during the installation. I’ve not had a Windows installation for several years now. If you don’t know whether you encrypted your drives or not, then you likely didn’t. Either way, if they are it makes figuring out their correct ID’s quite complicated and confusing, which was part of the issue. All the related guides to that topic sort of assumed I already knew what the hell I was doing, hence why I tried to ask for help.
Sounds like coil whining to me too, albeit a pretty loud one. It’s typically GPUs and / or PSUs that are the culprit when they’re under load.