I received my Inspiron 3891 on Friday 4-15-22. Performed all the updates yada yada and installed my two 8gb sticks of Crucial ram and the PC boots fine. Saturday my PC decided it wanted to update the bios to v 1.5.0 and I was like great, here we go. Happy to say no problemo after update. Loving this PC so far and sorry others ran in to a problem with their 3891's. 
Dell rolled out a new bios upgrade today, v 1.60. Have users who posted having conflicts not booting without using one stick of shipped ram been addressed and fixed with this upgrade? I have a 3891 arriving within the next few days and I already ordered Crucial ram upgrade.  
Inspiron 3891 Ram Issues Fixed?