PC failing to post

Hey all I’m having an issue I’m needing help with, my pc won’t post at all, keyboard and mouse aren’t getting power, ram isn’t on the proper color it’s cycling through rgb at default, I did try using integrated gpu for a boot but I have 2 monitors one on igpu one on dgpu so that shouldn’t be the issue anyways, and ideas? Not seeing any light on mobo, I’ve been told it could be cpu/ mobo, but how would I be able to tell which it is?