[kwlug-disc] Strange poweron problem

[B.S.]

On 07/25/2016 10:59 AM, CrankyOldBugger wrote:
> I have an older machine running Ubuntu 16.04.  I'm having a strange problem
> with booting it.
>
...
> Sometimes after I do manage to get power on and we go through the POST
> Ubuntu will get stuck, but a repeat of power off, power on, unplug USB
> cable seems to clear that up.  I don't think this is related to the power
> issue but I can't rule that out yet.
>

Anyone know if any recent updates have come down involving USB hardware, 
particularly around USB 3?

...
> If I try to power on from cold, the power switch does nothing.  No lights,
> no noise, nada.

This feels more like a short than anything else. Or you don't have the 
bios set to power up at power on (i.e. after a power failure) - but that 
feels unlikely as it would always have worked this way, and you wouldn't 
have asked as it would be your normal.

It doesn't feel like a cable short, as you reported the issue remains 
regardless of which end of the usb cable you leave connected.

I assume the hub and computer are on different power outlets, and when 
you say power on from cold, the hub is powered on throughout and you're 
not talking about turning a power bar on/off into which both are plugged 
- power on is from the computer front panel power button itself.

> ... But if I unplug the USB cable in the back, the power
> switch lights up and away we go.  The USB cable in question is the only USB
> device attached, and it goes to a USB 3 hub on the desk which currently has
> my keyboard and mouse plugged in.  (It doesn't matter if I unplug the cable
> from the back of the PC or the hub itself, the results are the same.)
>
 > ...
>
> Any ideas?

First question is ... has anything changed recently?

I feel your pain and bafflement ... 3 computers here don't come up 
properly after last nights power failure.

In any case, see if you can narrow down the culprit. Different behaviour 
if you?:
- use a different USB port? USB 3.0 should bring nothing to this party 
for just a keyboard and mouse.
- unplug the hub's power? (Nor should hub power matter, for this case.)
- direct connect without the hub?
- if it follows the hub, put both devices direct, with the hub 
connected, then walk back to where you were until the problem reappears.

i.e. which component does the problem follow?