My newly built PC won't turn on

[Butterallday]

I was building my PC and I plugged in all the wires to my motherboard from my PSU and it my psu doesn't turn on but when I tried turning it on with the paper clip test it did it worked perfectly fine so does anyone know what is causing the problem?

 

[pug_s]

What kind of components do you have? Have you connected all the connectors for the F_Panel specifically the power switch?