ATX connector not the same as MB

[sundance]

The 24v CPU connector is different on the Gigabyte motherboard I just purchased ( Z370P D3) than the connector on my Thermaltake ATX power supply (SP-500AH2NKW), also just purchased? Do I need the 2 pin part that is separate from the other 6 pin connector or is the 6 pin conn. all I need? The MB has one sq. and one roundish for the 2 pin connector and the power supply connector is 2 roundish.

Thanks