Question PC losing power in boot up

[L0cks]

Hey Guys!
So I've just done a PC upgrade and during boot up my PC briefly has no power for about 3 second, all fans go off and everything and the PC still continues to boot then runs fine. I used to have a i5-4460 and now running and Ryzen 7 3700X with a GTX 1660Ti 3x 120mm fans and the new Wraith Spire Cooler all on a Corsair CX600M PSU. It should be all good power wise and all my connections are pushed home. Any fixes or is it all good?
Cheers

 

[L0cks]

Expanding on that - I just did a reboot and it almost looks like it drops power to 50% almost, my LEDs in the fans dim drastically for example