Mining with 27 GTX1070 but I have 32GTX1070 HELP ! reward in ETH !!

Hi steemians, this post is to ask for help for the Steemit mining community because I cant make work 8 GPU in each rig, i have Z270A as a motherboard and I can only mine with 7GPU in each rig, i dont know why it doesnt detect the 8th card... I will be mining for 2 week long the proportion of the 8th card in each rig (in total 4 gtx1070 GPU mining for 2 weeks) for the person that helps me to make it work, as a thank you for helping me, if you have any article that can help me, or experience with this kind of issues that maybe can explain me what im doing wrong, I will be really thankful with the person. We can skype if necessary so i can give more details, thanks, have a nice day