Not sure if I need this extra connector

[AFellowGamer]

Ive recently bought a SeaSonic XP-860W power supply and the main power cable for the motherboard has 2 separate connectors for the power supply. One connector is an 18 pin and the other is a 10 pin. The manual says that if my build needs the additional power I should plug in both, if not then only the 18 pin. How do I know if I need to plug in both or just the 18 pin

 

[aonor]

Can you give us your motherboard name?

 

[AFellowGamer]

Can you give us your motherboard name?

asus p8z77 ws