I’ve noticed this interface banner on ASA5508-X while investigating reports of users being disconnected. CRC errors indicated the issue but it was unclear if it is hardware or perhaps a patch cable related.
sh int gigabitEthernet 1/1
Interface GigabitEthernet1/1, is up, line protocol is up
# Attention: This interface is located in a PCI-e x2 slot. For #
# optimal throughput, install the interface in a PCI-e x4 slot #
# if one is available. Refer to ‘show controller slot’. #
Hardware is Accelerator rev01, BW 1000 Mbps, DLY 10 usec
Full-Duplex(Full-duplex), 100 Mbps(100 Mbps)
<snip>
33568 input errors, 1883 CRC, 31685 frame, 0 overrun, 0 ignored, 0 abort
0 pause input, 0 resume input
0 L2 decode drops
Turned out to be an indication of speed or duplex mismatch because the interface was set to 100/Full. Once changed to Auto negotiation CRC errors cleared but not the banner. A reboot will most likely clear it.