Question pc turn on automatically when plugged in?

[benyaminj]

my pc when Power Supply On automatic Turn on.
when my pc is shutdown and i turn on pc system after 1 second it turn off again. Turn on and it works without any problems .

I'm really confused
My system is new .

GP650A-UK PLUS
B360 HD3 rev. 1.0
Coffee Lake Core i5-9400f
Vengeance LPX 2400MHZ DDR4 ( 2*8 )
970 EVO PLUS
vga:GeForce GTX 1070 GAMING X 8G

 

[Vic 40]

Have latest bios?