5

I'm having an issue on Windows 10 related to an external monitor (LG 27UK850) and power savings mode.

Issue Details

When the power savings for the screen kicks in after 10 minutes both the laptop screen and the external monitor turn off. This then starts a cycle where the monitor will turn off (triggering the device disconnect sound) and 30-or-so seconds later the monitor will wake up again (triggering the device connected sound).

Neither the external monitor nor the laptop screen show any images though - instead the external monitor simply powers on and shows a lit-up black screen before flashing an on screen display message that there is no signal and shutting down again. The laptop display itself remains off.

This cycle repeats regularly every 30-ish seconds causing a near constant disconnect/reconnect sound to play along with the monitor waking and sleeping.

The LG monitor has a built-in USB hub but I don't have any devices connected to those USB ports at all.

This ONLY occurs when connected via USB-C. The issue does not occur over HDMI. I'd like to solve the USB-C issue as I flip between PC and Mac and the single cable solution is both clean and convenient.

Update 24/09/2020 - I have tried using a USB-C (laptop) to HDMI (monitor) and the power savings works as expected. It is definitely a USB-C to USB-C issue.

My Setup

The laptop is a Razer Blade 15 Advanced mid-2019 model with RTX 2070 Max-Q running Windows 10 Professional. All OS and nvidia updates are installed. The laptop is plugged in and not running on battery.

The monitor is an LG 27UK850. Windows 10 initially showed this as a Generic PnP Display in Device Manager. I installed the latest drivers from LG - the issue persists.

What have I tried?

Monitor settings:

  • Deep Sleep Mode: I set this to ON. When set to ON it turns off the USB hub as well as PowerDelivery.
  • SMART Energy Saving: OFF

Windows 10 tests:

  • In Device Manager I have tried disabling the USB hub on the monitor. I thought maybe this was causing an issue but it didn't change anything.
  • Updated the monitor drivers in Windows 10 with no impact.
  • Tried disabling USB Selective Suspend Setting under Advanced Power Options (in case the USB hub really was causing some issues)
  • I set the Sleep and Screen time to both be the same amount under Power & Sleep setting in case there was some weirdness with the screen sleeping but the laptop still running.
  • The monitor has built-in speakers that I never use. I even tried disabling the audio device just in case.

I have zero issues when my MacBook Pro (2018) goes to sleep using the same USB-C cable and monitor. Power savings works under Windows 10 if using HDMI.

Is there anything else I could try to get this solved and working via USB-C?

39digits
  • 151

4 Answers4

1

Having the same issue for over a year now. Same monitor, Lenovo X1 laptop. The constant device disconnect/reconnect sounds at night were literally driving me crazy. The only solutions that worked were:

  • Connect via HDMI instead of USB-C
  • Mute the speakers, or change the device sounds to None (which disables them for all devices). This doesn't really solve the problem, it's just a workaround.

One hint that may help others in diagnosing the issue - I used the UsbLogView tool from NirSoft to see which device is causing the problem:

The disconnecting-reconnecting device is an LG device that is built into the monitor and connected to the USB hub on port #4 (an internal port that you can't see). It's a USB composite device hosting a HID and a serial port.

The main device identifier reads: USB\VID_043E&PID_9A39\008NTBKD7669 (the last part is the serial number of the monitor, VID 043E is LG Electronics and the PID is not listed anywhere).

I have no idea what this device does, so I tried disabling it in Device Manager to see if that solves the issue. I'll post an update if it helps.

Update - disabling this mysterious built-in device solved the issue with no apparent effect on the monitor's functionality.

Licht
  • 11
1

I have a similar case. My specific setup has HDMI but I don't think it plays any part.

My monitor from Dell has an "Auto" option in input selection. When my computer goes screen-off standby, and the monitor loses signal, it will loop between HDMI/DP/VGA inputs indefinitely and looks for any inputs. Adding to this, when the monitor switches from HDMI to DP and back, it will "shutdown" the previous input port. That "shutdown" event triggers the Windows "device disconnected" event. Immediately Windows responds with a screen-on wakeup action. The monitor picks up the HDMI when it circles back and there's a "device connected" event.

For proof, I switched from "Auto" to "HDMI" input. Never the same issue any more.

Yvon
  • 293
0

I have literally the same problem. Same monitor + HP Spectre x360. Only workaround I found so far is to enable a blank screen screeensaver. It still shines the backlight but is much better than the constant flashing.

Another thing I am trying is to use the Turn off Screen.bat file, but the monitor still wakes up after 20 minutes or so...

Jan Praus
  • 11
0

I had a similar issue but my monitor would go blank, then come on and stay on. Since you found a solution, this is for those that are not using a hdmi cable. Try setting your display to turn off before your screen saver. It won't totally solve the problem because your screen will turn on again, but it will only be for a moment and then it will go back to sleep. You can also disable the sound associated with connecting a new device so you don't hear when it comes back on.

ken
  • 1