I have been testing for a week with both Optiminer and Claymore and cant seem to get a stable rig with 7 GPU's. I have been testing with two identical rigs and both have issues with GPU2 not matter how they are configured. Ubuntu 16.04 Server, Desktop, Legacy, UEFI all have same issues. I am coming to the conclusion that a 7 GPU rig is just not possible with Ubuntu. If I disable GPU2 both miners run like a dream. GPU2 is located in the last PCIe slot on both my MSI Z97 Gaming 5 MBO's.
Perhaps its just my MBO.
Anyone else have a 7 GPU rig running on Ubuntu?