ROG Strix B450-F Gaming - DP and USB-C to PC

[Orangenbaum]

Hey, having a ASUS ROG STRIX B450-F GAMING, Mainboard with a Dell U2421E w. integrated USB Hub. Setup is:

All peripherals are connected to the screens USB Hub. Screen is connected to PC via DisplayPort (graphics card) and Upstream USB-C to the mainboard (for the keyboard etc.), as well as DP forward to 2nd screen. I regularly have to replug the USB to other PCs (switching between 4 pcs, all others are connected via USB-C only (no DP)).

Everything worked fine, but stopped working last week (Started with short disconnects into a full on stop two days later). The PC with DP does not recognize the USB Hub anymore. Error in device manager is: error when requesting a device description.

Everything still works with all other PCs (No DP/USB Dual connection as mentioned). DP still works fine if I use the peripherals plugged into the PC on their own (not an acceptable final solution, too much plugging).

Fixes I tried so far:

1. Checking USB connections (its all fine)
2. Using different USB Ports
3. Reinstall USB Drivers, Tried updating first then reinstalling
4. Patch and update BIOS
5. Set windows back
6. Update Windows to W11
7. Using a direct DP to USB Cable through the graphics card)
8. Booting Linux from a USB Stick (No error but does not recognize the hub as well, I might try this again with Ubuntu as Dell provides a Ubuntu driver)
9. Changed Windows USB Power settings
10. Changed BIOS USB Settings (Not sure if I checked everything)

What else could I try? Any idea why this happened out of nowhere?

Thanks in advance

[achugh]

Hi @Orangenbaum, I am sorry to hear about your troubles. I have two DELL monitors at home so I am familiar with DELL Hub software and the UI Menu. I do not have your exact same monitor but I believe what I have is going to be close enough.

How have you connected your DELL USB-C Upstream port (this is port #5 for your monitor manual on PAGE 10 of 77 at https://dl.dell.com/content/manual73970927-dell-u2421e-monitor-user-s-guide.pdf?language=en-us)? I am asking which port on the PC did you connect this cable into? Is it the one of the RED USB-A ports, the UBS-C Port or the BLUE UBS-A port on the back of your board? Or did you connect it to some other USB on your CASE in the front or side? Are you using any KVM switch since you mentioned you are sharing your monitors with 3 other PCs in your setup.

Did you install any recent monitor firmware on either of your monitors?

Have you tried to disconnect the DP Forward monitor and tried with just 1 monitor? When you say DP Forward, does this mean you connected a DP cable from the PORT 8 of your U2421E to another monitor's DP IN port?

To answer your question around what happened really needs to come from you as you would be best to recall what part of your system setup really got updated or changed that is causing issues since none of us really understand your setup fully yet. We will work together to understand what is connected where and help you figure out what to do next to get you back into your preferred working state.

[Orangenbaum]

@achugh: Thanks for taking the time, highly appreciated

yes everything is plugged into Nr5. (USB Upstream) .The setup works for USB-C Only connections (without Display Port). I tried to explain the setup further with this genius drawing:

Blue is the USB Connection with upstream (not uplink, typo)

Hope this makes it more clear

Port Wise: Yes DP Ports are correct (everything works when i use the USB-C upstream only, as from the laptops or surface). The USB just stops working when the video signal is coming from DP.

Ah this is obviously unclear (Sorry): DisplayPort works well with PC  (forwarding as well, so I can see both screens), what doesnt work anymore (it worked for around 4 month) is the USB Signal onto the mainboard of the gaming PC. So I cant use my mouse/keyboard etc anymore if plugged into the screen. (only when connected to the gaming PC, laptops works just fine). And I can still plug keyboards / mouse onto gaming pc and it works.

Thats why I thought it might be a motherboard or software issue.

(Ah the second USB-C to USB-A connection is a 3.2 cable with a 3.1 connector (as usb input is 3.1 as well).
Cable and connector: https://www.digitec.ch/de/s1/product/inline-usb-32-verlaengerung-2-m-usb-31-usb-kabel-13266974?suppl...
https://www.digitec.ch/de/s1/product/powerguard-usb-a-zu-usb-c-90-grad-winkel-links-flach-adapter-us...
(Yes the adapter wasnt the best choice, but it worked)

Best Regards

Anjan

[achugh]

Hi @Orangenbaum , thank you for sharing this diagram. This makes it lot more easier for me to understand your setup.

For reference, I have a DEL U3223QE and my user manual can be viewed online at https://dl.dell.com/content/manual12003775-dell-u3223qe-monitor-user-s-guide.pdf?language=en-us. When I compare this manual to your monitor manual at https://dl.dell.com/content/manual73970927-dell-u2421e-monitor-user-s-guide.pdf?language=en-us I noticed that on your manual page 55 of 77 you do not have PIP/PBP and USB menu categories (see my manual at page 66 of 96). It is quite possible that your monitor may have received firmware updates and have these additional menu options and the online manual is not updated or I am looking at the older version of your manual.

I do want to share that since your monitor has only 1 USB-C port (not like 2 USB-C ports I have) it is possible that when you switch your input to DP, the USB-C port gets deactivated due to some menu option as it is only looking for video signal. On your surface pro and laptops since you are connecting to the monitor via USB-C using VIDEO+DATA configuration your USB-C port works and hence the hub works for you. This is why I am asking if you have the USB option on your monitor even though your manual online does not show it. This option is where I control my USB configuration on U3223QE.

I also recommend that you check your monitor's firmware by installing the Dell Display Manager application in case a newer firmware is available to add the USB menu which gives you lot more control of how USB ports work (VIDEO or DATA or VIDEO+DATA etc.)

Here is what I am thinking you can try assuming there is no special USB menu to control things.

Did you try doing a FACTORY RESET of your monitor from the OTHER menu (see page 63 of 77 about this menu option)? Only reason I am thinking about this reset is in case you updated your monitor's firmware.

If you are okay with doing a factory reset to reset all the settings to defaults, I recommend that you disconnect all the cables and have only the DP cable from your PC to your MAIN monitor connected (make sure you disconnect your 2nd monitor as well). Since your Keyboard and Mouse are not working, temporarily you will need to connect them to your PC. Then do a factory reset on your MAIN monitor. Now connect your 2nd monitor to the MAIN monitor. Next connect your mouse to the MAIN monitor and see if it begins to work. If it does, then you connect your keyboard. Once everything works with your PC, try RESTARTING your windows to confirm things work after a restart. Finally if restart works as well, SHUTDOWN you pc, wait for 1 minute and now POWER ON your PC to test that a cold boot works as well. At this time, you can shutdown your PC and now connect you Surface Pro and finally connect your Laptop.

If you are not interested in doing a full reset, do not connect your PC, Surface Pro or Laptop to the MAIN monitor. Then on the MAIN monitor, I would at least go under INPUT SOURCE menu and choose Reset Input Source and then go under DISPLAY menu and choose Reset Display to see if these resets make any difference. After doing these resets, make sure you physically remove the POWER to the monitors (both of them) by unplugging the wire from the WALL. DO NOT JUST USE THE POWER BUTTON ON YOUR MONITOR TO TURN OFF. You need to remove the power to do a HARD MONITOR reboot. After you have removed the power, wait 1 minute and then connect the power to your 2nd monitor first followed by the power to your 1st monitor and now start testing using your PC, followed by Surface Pro and then your laptop.

FYI, since you are using extension USB-C wires for which you send the links, I do want to let you know that the official USB-C cable specification from the USB consortium recommends that a USB cable carrying video data should not be longer than 1 meters and for a cable carrying data (without video) should not be more than 2 meters. This does not means longer cables are not available or you cannot use them. It simply means that you now have chips inside the cables in the plastic area that you hold to pull or push the cable to help with signal transmission and sometimes these chips cause more problems. Since the cable was working for you, I am not doubting that is an issue for you. This is something for you to keep in mind.

Good luck and I hope this information helps you find out the problem and fix it as well. If you are still having issues, please share back what you have tried so we keep eliminating things till we find what is causing the issue and help you resolve it.