Switch Boot Drive

So i have a intel i3-4150 with Intel HD 4400 iGPU , i do not have any discrete gpu. My dad has an intel i3-9100f and a GT 710. As his PC is faster than mine , i wanna switch his PC with mine , but he says he has important files in his PC. So I wanna know whether i can switch the pcs with the...

This probably sounds weird, but I have medium pitched hum that comes from my case and the hum instantly disappears when I remove the side panel. Has anyone heard of this before? The case is a Corsair Obsidian 450D:??: Edit: It's possible that the hum is present somewhere inside the case and...