USB ports

you should able to see how it is connected in the OS, devicemanager on windows, usbview et.al. in linux

I think everything but the cheapest stuff will have a load switch per port

It probably depends on age and number of USB ports.

Some of mine have two USB controllers one for the set of four or six on the back and one for the pair on the front panel.

When USB3 was new then almost certainly a separate device but in the latest generation of systems I honestly don't know.

On USB2 I suspect mostly they are pass through. USB3 can use higher currents and voltages that may be done by an external FET.

Might be easier to interpose a powered hub between the offending ports and whatever you want to connect as a means of extending its life.

Ah, yes -- I forgot there is a "view by connection" option (that is not the default). Thanks!

That's what I feared. It doesn't make sense for EVERY port to exhibit the same sort of failure (and for the OS not to be complaining about it!)

There are a mixture of USB2 & USB3 ports in each location. AFAIK, controllers are USB2 (EHCI) or USB3 (XHCI); while the XHCI could handle USB2 speeds/devices, it seems like one would *advertise* all ports served by the XHCI as "SS" (which is not the case, here).

Ditto. I'm not keen on taking things apart to find out.

I thought of that but she's already got quite a collection of kit on her desk and one more would just add to the confusion. <frown>

Taking Lasse's suggestion, I can see at least two EHCI and one XHCI. There are 6 ports on the rear and 4 up front. So, likely the XHCI conductors are split and the two EHCIO handle separate clusters of ports (front vs rear).

Her "problem" manifested in all of the USB2 ports which suggested the *load* was more likely the problem (unless there was a seperate LDO feeding just the USB controllers). USB3 ports had no problem.

OS did not throw an overcurrent warning (and shut down the port(s)). Yet, I can see the LEDs on the keyboard blinking randomly -- as if it was being plugged/unplugged rapidly (no OS announcement of this but I don't think the OS announces keyboard/mice events?)

She had the mouse plugged into one of the two USB2 ports present on the keyboard (seems a logical choice). So, the ONE connection from the keyboard was representing TWO devices/loads.

The absence of the overcurrent event suggests maybe the keyboard just couldn't handle the added load and *it* was misbehaving? An identical replacement keyboard exhibits the same problem. (though I didn't try to replace the mouse at the same time <frown>)

Dunno. I rearranged her cables so each device had its own port, keeping the front ports free for thumb drives, etc. This *seems* to work -- I'm sure she'll let me know if it acts up, again. <frown> (it is no fun being an IT department!)

I located an identical spare machine in my stash (actually, *two*!) so if it continues acting up, I'll just pull the disk and give her a "new" machine -- a lot easier than trying to install all her legacy software on a different make/model machine, given MS's fussiness!

It might be worth buying a USB power meter. It avoids a lot of guessing and costs very little. Some of them have USB-A and USB-C ports which covers all likely options. To avoid unnecessary cables I like to use a Bluetooth wireless mouse. Microsoft make some very cheap and reliable BT mice. They communicate with the BT transceiver inside the PC so there is no need for a USB dongle to communicate with the mouse. John

Yeah, though I've never had a need for one, until now. (All sorts of things I *could* buy in anticipation of needing them...)

No BT on her computer. She already has a cordless mouse and keyboard that reside in a desk drawer -- for use with a NUC that is reserved exclusively for ecommerce/banking (shares the monitor that she uses with her desktop machine -- previously used a laptop that lived on one of the desk's returns for that but laptops have tiny screens, icky keyboards, etc.)

I don't understand why the PC didn't complain of "excessive power" and shut off the port. So, I assume it is just a failing in the design of the keyboard (as it manifests with another identical keyboard). Hard to imagine putting two extra USB-A in the keyboard if they can't be *used*!

Perhaps I'll try booting a live CD and see if it provides more detailed diagnostic messages than Windows.

But, for now, she is happy. (emphasis on "now" :< )

Yeah, well that was a short lived "non-fix". <frown>

Even with the mouse off the keyboard, the keyboard has conniptions.

I've found a nicer AiO that would be a better "upgrade" for her. And, hopefully "close enough", architecturally, that MS won't throw a fit if I pull the disk from the old machine and pray for it to adapt itself to the "new" hardware. One less box on her desk has got to be an improvement!

(sigh) It is *so* much easier to upgrade a BSD box -- just pull the drive and put it in a new machine (of the same target architecture) and it will rediscover the devices present at each successive boot (not *remembering* any of them!)

I guess that's tonight's project...

A *copy* of her disk installed in the AiO seems to work. Windows claims to be "activated". A cursory look around suggests everything is intact (2T drive so I'm not going to kill myself looking in every nook and cranny)

I checked the Product Key in the new machine (after boot) and it is identical to that of the old machine. This suggests it is created at install time and branded onto the disk. Thereafter, windows must just *verify* that the BIOS allows that key, even if the actual hardware differs.

I'll set her old machine aside and replace it with the AiO and see if she notices anything misbehaving. Then, pull her "original" disk (figuring that will be the authoritative master if something goes south) and see if I can sort out what her hardware is claiming about the problem (I'll use a live CD so I can examine the more detailed log messages)