I tested and the B2 error goes away if I disable the LSI MegaRAID card. It has the latest LSI firmware. I have it configured to boot with CSM enabled, UEFI driver first and to load both the legacy rom and UEFI driver or I won't actually have the card available to boot from (the RAID 10 SSD disks serve as my system disk / application disk while the bigger drivers are for data). So the LSI card is the culprit or specifically the Legacy Option ROM is the problem because if I set it to boot without CSM (eventhough the LSI card should have a UEFI driver) then I have no disk drive to boot to (in fact I can't even see the options for the various boot devices in the Asus M6E BIOS).
Maybe I will remove it even though that kinda sucks having to move over to the Intel RAID stuff instead, but any suggestions that can save my setup is all too welcome.
List of USB connected items:
Logitech G710+ keyboard
Corsair M65 Mouse
And the USB 2.0 and 3.0 ports have been led out to my case which is a NZXT Phantom 820