Hi guys, I have a serious issue with my rig, and I appreciate if someone could help me.

I have a 12x GPU Rig, after around 10 minutes or more of mining the GPU 11 drop the hash rate from 26+mh/s to 18+mhs then this 18mhs is randomly getting on any other cards and then the rig reboot it self. the other issue is almost the same, GPU 11 drop hashrate to 0 a then restart the rig. this is happening with the normal version of smOS and the other with the Dag Fix. I already change the PCI riser and the USB cable but the problem persists.

My rig:
6x Rx 580 pulse 8GB
6x Rx 580 Strix 8GB
Board H110 Pro BTC+
8Gb Ram
Intel i3