How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

Hi, list My x86 machine(linux4.19) sometimes hangs, suddenly not responding in any way to the mouse or the keyboard. How can I investigate why it hung up? Is there extra information I can find for a clue? Is there anything less drastic than power-off to get some kind of action, if only some limited shell or just beeps, but might give a clue? Thank you for your attention to this matter.