Open the case and get your nose in close. You have to identify the location.
My cousin's Hp Pc,( Yes I no Hp lol) shuts off randomly and I know something is overheating because you can smell it burn and then it shuts down. The cooler the computer is the longer it runs which leads me to think that, either the CPU fan isn't work or its the power supply. I recently figured out it wasn't the CPU fan because I replaced it with an old Xeon fan that spins extremely fast and extremely loud lol. So I'm thinking that its the power supply... problem is I think I feel fan flow... I also had a thought that it might be the thermal paste that has dried up and starts to burn but I don't know if thats even possible... the smell that emits is really bad and felt around the case I can't feel whats hot, but I know that smell anywhere it is the smell of like burning/melting. Srry, first blog post, too long?