Boot hangs at "Updating CPU Microcode..."?

[Machupo]

I am running 11.3-RELEASE on an x10sdv-6+-tln4f board and have been getting occasional reboots, but the more pressing issue is that about 90% of the time, the system reboots and hangs at a step very near the end of the boot process (after pool import, after encryption) but not always in the same place. The last line is "Updating CPU Microcode..." and cannot be bypassed with a Ctrl+C. I cannot seem to find any documentation on this feature being an on/off toggle (which I could flip once I got it booted again) :/

I have a bios upgrade available for this board, but I'd prefer to solve the issue in the software environment, if possible, before I go to firmware as I did not have this problem in 11.2-U6.

I have been using freenas for nearly 5 years, but never really dug under the hood (mainly just nfs share and plex), so I don't know what I don't know ;) Thanks in advance!


Hardware specs:
Supermicro X10SDV-6C+-TLN4F
64GB DDR4-2133 ECC
Pico PSU 150
970 evo plus 250gb boot drive / cache (yeah, way overkill)
LSI 9305-24i (avago)
3x vdevs of 8x 2TB WD Blue m.2 SATA drives in Z2

 

[Machupo]

Went ahead and updated the bios / management engine. First boot went through the wickets successfully, so here's hoping that solves both the boot hang and the random reboot issues.

 

[Machupo]

So, it appears that the firmware update squashed the CPU microcode issue, but I'm still having random unscheduled reboots. Any tips on how to set logs that may narrow down the cause of reboots? No other systems on this circuit are rebooting, so it is not a power issue.

Thanks!