Seems like some underpowered from the board. Do you have a powered molex on the one that got the error?
https://bitcointalksearch.org/topic/--7216
this is my rig
like u can see on linux i can run 6 gpu without (gpu) problem (i have other linux problems)
btw on windows only 5 are working well
if i check under device manager i see 6 gpu and 1 with a red X and error code 43
i have 2 psu (1100+1000) 1000 is for 3 gpu 1100 for 3 gpu + mb
riser 1x powered under the 1000
riser 16x non powered (under 1100)
if i remove 1 riser 16x16x windows detect 5 gpu (2 with 16x16 3 with 1x16)
if i plug the 16x16 windows detect 6 gpu but 1 with error 43 and the gpu disabled is one of the 1x16
