The mobile phone makes a strange buzz.

This should be when the mobile phone is networking or sending and receiving signals, and the mobile phone interferes with the sounds made by some components in the mobile phone. Probably the part of the speaker close to the motherboard of the mobile phone, which is not easy to detect from the outside, just like the signal interference that appears when the mobile phone is placed next to the stereo when receiving short messages. It should be caused by normal cell phone signal radiation and has no harm to human body. Don't worry.

It can't be the problem of the silent part of the CPU, nor the hard disk. It is impossible to vibrate or make any noise.