How to test entire component's on Dell Motherboard?

Hi Friends,

Yesterday, i bought one second's laptop from my relative.  When i was googling, i found some software to check RAM, HARD DISK, etc. But i don't  know, How to check motherboard components completely.

I already knew dell diagnostic system check. and i tried too. Its shows no problem found. I want to know about something in-depth failure of motherboard internal components. 

Why i'm asking this question  which means lot of dell laptop's are power failure issues. Service center are said to people, change your motherboard that's the only solution for power failure.  

I want more to know about power failure issue or power IC failure ?

Could anyone help to find the solution for this issues...