Supermicro - Where does the "INT" cable go?

[On Holiday]

 

[Caged]

What lights up if you connect it to the power LED header on the board? If I had to guess I'd say it's for network traffic.

 

[Nikumba]

What case are you using?

 

[ZXSpectrum]

Its chassis intrusion. You should have a header on the motherboard.