Hi again!!

I've run into the same issue. changed CPU for G4400 and pc won't start!

If I connect only CPU and fan plus GPU,they start to run their fans automatically when switching on the power unit. But as soon as I connect one more cable (CPU power cable), it won't do anything,and when I try to start CPU it won't connect. What can it be??? What is it the most common issue or something that I might be missing??