hi, can someone tell me if there is a difference when using both 8+6pin on the nitro+ vs only 8pin?

my rx570 pulse has only 8pin and gets me 29.4MH/s so I wonder do I need both connectors to get the same hash on the nitro+?

the issue is that I can only buy the nitro+ but putting more than 4 gpu in the rig would require more then 2 psu