PCIe - Training error on device - Link degraded, macLinkWidth = x16, negotiatedLinkWidth = x8

i’ve placed a pcie raid adapter card with onboard ssd’s (AORUS RAID ADAPTOR built in with 4 x PCIe 3.0 512GB NVMe SSD) in a new (2020) Dell (Optiplex 7080).

the system boots fine most times, but it tends not to find the drive during a soft reboot, for example. it’s very temperamental on boot, but works fine once the OS is booted.

the built in boot diagnostics produce the following warning:

PCIe - Training error on device - Link degraded, macLinkWidth = x16, negotiatedLinkWidth = x8

is this warning related to the boot device being not found sometimes or simply indicating the card is x8 and not x16?

if unrelated, what could be causing the system to not find the boot device at times? i’ve checked and reseated the drives on the adapter, and the adapter within the pcie card several times.

thanks for looking.