How can I test CPU or MB

[freewill]

Hi guys

I wanted to check my PC,apparently there's sth wrong with it since it doesn't turn on the monitor whenever it restarts, based on the archive of this great site I checked the Graphic card and RAM. but I don't know how to check the CPU or mobo, could you tell me what I should do?

PS: I think I should buy new ones!!!

thank you guys