Hi Andonios,
I am a hundret percent sure that the sound is coming from the SSD because I plugged in the ssd without any enclosure while the system was already running. The sound was only there after I plugged-in the SSD to power.
Furthermore it seems like you are missing a lot of physical components that can make noise: Coils.
Coils can make sounds under certain conditions. This is a common case in certain combinations of mainboards and power-supplys.
In a very old system (I think it was Pentium 1) I could even hear if the CPU was idle (made a little sound) or busy.
There may be other electronical components that may create sounds in case they come in contact with high-frequency signals. Therefore don’t think that you know everything.
