How to repair no power computer motherboard. power Supply troublessooting

Hello, First check SMPS and then power cable. if its ok then check power supply on - off switch...then check IO IC . Two type voltage you found here. one stand by voltage and another PS ON voltage. If its Ok then Check PCIE slot pin no - B!) You found 3.3 volt here. and PCI slot Pin no - A14 you get 3.3 voltage here. if its ok then south bridge is ok. then remove 4 pin atx connector and power on the motherboard. If board is on means VRM section Is faulty. check VRM section.... If VRM section is ok then clean board ..... Thank you