anyone?

im having the wierdest problem with my 12 gpu rig...
specifications :
12 x rx580 8gb
4 gb ddr4 ram
g4400 cpu
2 x 850w psu
1 x 1000w psu
asrock h110 btc+
working on smos with 64gb usb stick
my rig is doing 350 mh/s stable for 5-6 hours but then 1 of the cards (only from 06 to 11) gets disconnected and turns to 00.0
or sometimes it might turn all og the gpu's from 06 to 11 to 00.0
i tried changing the cards, risers and the cables.
the only guess  i have is its the mother board.
does anyone here ever had this problem with this mothert board? or any similar problem with his rig?
if you have any advice i am willing to try anything, thanks in advance!!!