Wanted to share this with group because this had me thrown for a loop for the better part of three day & I know there are quite a few other homelab aficionados that repurposed these little thinclients because they are just so small & versatile.
TLDR: microcode update was to culprit. Hope dell either push an update or it otherwise get resolved or...I'll be unsecure, I guess.
Fixed it by rolling back to version 2:2.1-26.xs28.1.xcpng8.2
yum downgrade microcode_ctl 2:2.1-26.xs28.1.xcpng8.2
yum downgrade microcode_ctl
might work as well, but that really depends on your upgrade path.
Detail:
After a recent update I discovered that none on my virtual machines would boot save for one that would boot sporadically. It was accidentally set to pv drivers...not entirely sure how that happened, but it also could have just loaded that way when I imported the cloud image from Harvester.
The symptoms:
Not keyboard or mouse input for windows or linux.
Windows vms would boot & do one of two thing the screen would "Guest has not initialised the display (yet)" or get to the point where the drive was initialized & hang...they would basically max out what CPU they were allowed.
Linux vms would boot & always hang at the same place right after grub loaded initial ramdisk.
Try every bios setting I could no joy.
Hope you other poor stuck soles stumble of this & save your self's some time.