Usb 2.0 And 3.0 Same System Problem

Posting this here as I don't need help, just sharing info.
We had a couple of systems with 2.0 and 3.0 USB on the MB. One ran flawlessly, the other would fail to boot sometimes on a cold start, but come right up with a reset. The boss has given up on Win 10 for now so I had some time to look at this. The offending system had a 7 port 2.0 USB hub. Upgrading the hub to 3.0 7 port fixed it. Somehow the 2.0 / 3.0 USB combination got into a loop in the BIOS. The mouse, keyboard, speakers and headsets would blink every ten seconds while the boot tried to finish.
I am assuming the devices that are 2.0 and 3.0 compliant got recognized as one then the other. Or it may be the Windows USB stack rewriting infinitely as each USB device is recognized and dropped from 2.0 to 3.0.

Greater minds can explain it, I only offer that if you have a system that hangs at boot, strip out the USB devices.

 

USB 3 provides more power than USB 2. For a 7-port hub that would matter.

 

How would that prevent a boot but work on a reset Mimsy?

 

When you hit the reset button it's usually because it powers on but won't boot... right? Consistent port over a longer stretch of time might make a difference. I know for a fact it often does on SSDs and they're just a more complex form of flash drive.

Most common reason I've seen for why a system won't boot when there are USB drives plugged in, is because the boot device scan portion of the POST sequence gets stuck because of too much to scan. If the BIOS was made for UBS 2, and the devices are USB 3... who knows? I'm making educated guesses at this point, for all I know the secret is a power setting in BIOS or a driver registry entry.