XPS 8910, Rear USB 2.0 ports not working?

I assume you hit F2 to enter the BIOS and get stuck on the Dell logo screen. This tells me that you did not successfully enter the BIOS and your problem is definitely not related to Windows or Windows drivers. If I remember correctly I believe you stated that you had no issues with the mouse using the USB 2.0 ports, so I think that rules out an hardware issue with the ports. (Unfortunately, I don't think there is a way to test the mouse in the Dell BIOS.) The only thing that remains I believe is that the BIOS software is corrupted in the way it handles the keyboard when connected to the USB 2.0 ports although I don't see how that is possible since the keyboard software should be the same no matter what port it is connected to. Did you also happen to try your other keyboard? At this point, even though there is some risk, you could try to re-flash the BIOS or you need to contact Dell for a new motherboard.

@vtoy

Thanks for the replies.

No, it seems like simply plugging in the keyboard in the 2.0 literally won't get past the startup screen.

(The "Dell logo screen" is that first thing you see when you turn the computer on.) You usually see that spiral of circles under the logo indicating that it's starting up; plugging in the keyboard prevents that "spiral", and as mentioned, unplugging the keyboard at this point makes the spiral appear and start the start-up process normally.

Is re-flashing the BIOS that risky? And as you mentioned, if the ports are physically ok, is it something that requires a new motherboard?

So, it will not recognize K+M attached to the USB 2's when booting, nor work for Windows.

BUT, I can use a flash drive under Windows just fine -- detects, reads, writes, ejects, etc.

ALL the above fixes have been done.  Have done a clean install for the latest 1703 Developers version of Win 10 Pro x64 and STILL same result -- NO K+M support on the USB 2's.

The Dell logo screen indicates the start of the BIOS and the spiral of circles indicates the completion of the BIOS and the beginning of the loading of Windows. If you wish to enter the BIOS you have to hit F2 at the very beginning of the Dell logo screen otherwise the BIOS runs and Windows starts.

There is always a risk flashing the BIOS and failure means a new motherboard will be required. I should also say the with a BIOS update I am not sure the entire BIOS is replaced or only a portion and if it is only a portion then it may not be the portion that is corrupted. Based on the fact the you can plug a mouse into the USB 2.0 port and have no problems I have to conclude that the 2.0 ports can physically communicate with a USB device. This leads me to conclude that there is a software issue and the only software that is running is in the BIOS. The only way to replace the BIOS is to flash it (risk) or replace the motherboard.

If your system is still under warranty you should contact Dell and get a new motherboard. If your system is not under warranty you could probably use the USB 3.0 port for the keyboard as long as you can enter the BIOS with the keyboard connected to the USB 3.0 port.

I also have ports that fail during boot.  This is when I first noticed the situation.  My machine had rebooted and I could not do an F2, F12, or anything else to interrupt the boot process.

See this thread about a similar issue although the issue is only with the keyboard; en.community.dell.com/.../20016599 .

Can somebody test this?

Connect an externally powered USB2 hub to one of the rear USB2 ports and plug the hub's power brick into the wall. Now connect the mouse and keyboard into the USB2 hub.

Boot the PC and see if M+K work via USB2 now...

My Dell tech contact wants you to try this:

* The XPS 8910 is turned off

* Plug the USB keyboard into any of the four blue rear ports

* Plug a USB mouse into the left rear black USB port

* Turn the XPS 8910 on

* Does the USB mouse work?

* Disconnect USB mouse from left rear black USB port and plug into right rear black USB port. Does it work?

Now repeat exactly the same test, but this time plug the USB mouse into any of the four rear ports and plug the USB keyboard into the left rear black USB port, etc...

Post the results of both tests here.

My Dell tech contact requested that you try this:

* The XPS 8910 is turned off

* Plug the USB keyboard into any of the four blue rear ports

* Plug a USB mouse into the left rear black USB port

* Turn the XPS 8910 on

* Does the USB mouse work?

* Disconnect the USB mouse from the left rear black USB port and plug it into the right rear black USB port. Does it work?

Now repeat the exact same test, but this time plug the USB mouse into any of the four blue rear ports and plug the USB keyboard into the left rear black USB port, etc...

Post the results for both tests here...

I have had the exact same problem and lack of success.  I have two (2) XPS 8910's.  One works perfectly, the other has this USB 2.0 problem.

I'm still waiting for DELL to come up with a solution.

I have done all the BIOS upgrades, chipset updates, etc. -- NO CHANGE in the  anomalous behavior.

I am now wondering what I can replace on the MB to make things work?

BUT, Did I understand ghost correctly above?

HE SAID:

"... What's ever weirder is that if I plug a USB hub into one of the USB slots that is having the issue (the "dedicated" keyboard/mouse slots), then plug the keyboard into that hub, it also works."

So, does this mean I can plug a USB hub (of which I have several USB 2's & 3's) into one of the USB 2.0's and then plug my mouse & keyboard into that hub, then I will regain usage of the USB 2.0 port?

That would be a help in salvaging my ports for other needs.

I suggested connecting a hub to the USB2 ports in this thread:

en.community.dell.com/.../21011406

Have you run the test that I posted above on 7-29-17 from my Dell tech contact?

BTW: If any of you haven't resolved this problem and you're still under warranty, contact  Dell Tech Support asap.

You might need a new motherboard...