How to repair motherboard

[SandeepKumarSiwag]

When I turn on PC there is no beep, screen goes blank. CPU fan works properly.
I clear CMOS several times, I don't know whether I put it right or wrong.
I think either my memory modules are defective or memory. How could I figure out which part is defective?

 

[inzone]

What motherboard do you have.