Supermicro stuck on 91
Solution 1:
I had a real problem with this on a Supermicro 6017B‐URF hanging at the "System initializing........91". Lacking the tools to complete all the recommendations in supermicro.com/support/faqs/faq.cfm?faq=18922 we fixed the issue by removing the clock battery, attempting to boot without it in place and then re-inserting the battery and rebooting.
Solution 2:
Had this problem when the video output was to "UEFI" in BIOS. Resetting the BIOS to defaults (by removing power and the CMOS battery) fixed it by reverting the BIOS video output to "Legacy".