my gpu is amd rx 470 oc sapphire 8gb , it has both 8 and 6 pins connector , as i know this card power is 150W , and the 8 pins is 150 W so do only connect 8 pins or connect both 6 and 8 pins to the sockets ?

You have to use both jacks. Standard diggers have six legs, but there are also some with eight legs. Be careful when assembling coin miners to avoid unfortunate damage.
both jacks