[SOLVED] Motherboard Power indicator still on, even though there is no power connected

[DDx76]

I'm having issue with my first build, my motherboard (Asus ROG Strix B360 H) power indicator (bottom right) still on, even though there is no power connected to my PSU (Seasonic Focus Plus 750 Gold), but after a while it turn off..

Can anyone explain it ?

 

[DDx76]

 

[DMAN999]

Power is still retained in the motherboard's capacitors and slowly drains.
After you disconnect the power supply you can hold in the power button to help drain the power from the motherboard a bit faster.