3 nVidia GPU, only 2 running

hi guys,

i got a z170 pro gaming motherboard, 3 nvidiacards connected (970, 1060 and 1070). im getting error code 43 in windows 10, see screenshot here:

Imgur

can someone tell me how to fix this?

thankd in advance

Will the 960 run solo?

Will it run solo in the same slot its in? will it run solo in one of the other slots?

Will it run with the 960 and the 1060 together?
what about the 960 and 1070 together?
have you swapped out the 960 with the 1060 slots?
are you using risers? if yes what version?

what drivers are you using?
have you disabled onboard video in bio's?