Those server/motherboard has latest BIOS Rev. 1.1a from SuperMicro web site.
Please change BIOS menu \Advanced \PCI/PnP Configuration \SXB1 Configuration = 2x8
But it’s really strange that when we use “AUTO” we have this issue! This is depending on the riser card. Some riser card support Auto-switch feature, others need to manually change it.Tags: ARC-1212, BIOS, firmware