Agree power supply can caused weird faults. I had one where the PC could not be turned on with the front panel switch, but would turn on if the main AC outlet switch was cycled. Friend had same PSU (Seasonic) they no longer needed, but was identical model and age as we had got a deal by company to build our two PCs at same time to same spec, so he sent that to me. Tried that. Exactly same fault, so assumed PSU not at fault but then PC decided not to turn on at all. Changed motherboard, same fault again. As a last resort I bought a brand new PSU (Corsair). Turned on, all sorted. Incredibly, friend's PSU they had lent me must have had exactly the same fault on it. What's the chance of that?!

Had the new Corsair PSU now for maybe three years. No issues whatsoever. Possibly illogical, but will probably avoid Seasonic PSU again in future!

Max