Contacts on the power supply

On the PSU, and the CPU 4x2. On the motherboard 8x2 (pw1 and pw2. I know that pw2 is not required, connect only to pw1. The problem is that the contacts from the first part are similar to those of the mother, and the second half is different. The first half hooked up, the second is also inserted, but confusing, which is different form (in block 4 of the hexagon, the mother of 2 hexagons and 2 squares).

Question: do I have to plug in the 2nd half. If not necessarily, then is it not dangerous to connect a second, different, half.





1 - hexagons
2 - squares (if the photo suddenly is not visible)



Contacts on the unit (all hexagons)