[Locked] Sudden shutdown

Actually, I'd say a problem with the PSU is more likely than a problem with the processor.

The fact that it happens at random including while "[he's] turning it on" means that it won't be over heating issues. (As it wouldn't nearly have enough time to over heat, furthermore, if it over heats then why not until later other times?)

I'd assume the OP's computer comes from a store (prebuilt) most likely somewhere like best buy or future shop. Often times, in stores, the CPU, GPU and RAM are most heavily advertised while the rest of the system is left unknown. Manufactures often cut corners and cost by using knock-off power supplies which often lead to problems like this.

However, without a list of hardware and a little more detail on the problem, nothing can be certain.