XPS 8940, screen black after overnight sleep

Update: 

Problem remains after sleep for any length. Have to unplug/plug cable from HDMI port on PC to remedy.

@Mebe2003 You should probably not unplug/plug the HDMI cable into the monitor without first unpluging the power cable. The manual warns 'Do not connect the power cable before connecting all other cables'. When the problem occurs have you tried turning the monitor off and then back on? What is Source Detection on the monitor set to, Auto or Manual? Have you tried changing this setting?

@Mebe2003 There is also a driver for this monitor but I am not sure what its purpose is. Apparently, according to the manual, the driver only supports up to Windows 8 and does not mention Windows 10.

Check your BIOS settings for Multi-Display and Primary Display. 

Monitor source is manual set to HDMI (was auto). Turning monitor off/on = no change. Same monitor from previous PC that had no issues after sleep.

@Mebe2003   - Have you tried setting Hibernation to Never on same screen where you turned off Hybrid Sleep and PCI Express Link State?

Followed another post by you where you suggest to disable or turn off the following:,

Hybrid sleep, Hibernation, USB Selective Suspend and PCI Express Link Management

Active power plan was balanced and these options were present.

New power plan is High Performance and some of these options are not present.

Update on Monitor driver: Used both Samsung driver and Universal PnP. No change.

BIOS Primary Display is set to UHD Graphics (was auto). No other options present since no card.

Also changed Device Driver -> Monitors from Samsung to Universal PnP. No change in behavior.

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@Mebe2003 wrote:

Followed another post by you where you suggest to disable or turn off the following:,

Hybrid sleep, Hibernation, USB Selective Suspend and PCI Express Link Management

Active power plan was balanced and these options were present.

New power plan is High Performance and some of these options are not present.

Update on Monitor driver: Used both Samsung driver and Universal PnP. No change.

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What happens if you just press/release the power button on PC rather than holding it to force a shutdown? Does the monitor wake this way?

I assume this monitor has its own On-Screen Display (OSD) that's opened by pressing a button(s) on the monitor. Open the OSD and find the screen for video port selection. If it's set to "Auto", change that to HDMI and see if that helps.

You can always disable hibernation this way:

1. Open a Command prompt window, Run as administrator
2. At the prompt, type in: powercfg.exe /hibernate off and press Enter
3. When it's done, close the CMD prompt window
4. Reboot and see if that helped

Ran 'powercfg /hibernate off' earlier but forgot to mention.

Set Monitor to HDMI only (was auto).

Tower is waking up and power is sent to monitor (goes from black to glow). Monitor light blinks when on standby and goes steady when tower wakes up. But it appears no data is being sent to monitor.

Wiggled connector to see of connector/pin issue. No change.

Will try momentary press of power button to see if any changes.

However this morning, no failures. Tower starts, monitor light goes from blinking standby to steady, followed by normal desktop screen.

Since only fails half the time, need to let recent changes soak. Only put PC to sleep at end of day but will also try to invoke sleep mode during day time.

Update #2 after several days of testing.

Over the last several days, put PC to sleep for various periods then awaken using ONE of the following:

1. Momentarily pressing PC power button fully awakens PC and display is normal 100% of the time. No issues.
2. Pressing a wired keyboard button fully awakens PC and display is normal 100% of the time. No issues.
3. Pressing a wireless keyboard button appears to only wake up half of the PC. Fans and HDD start but some ports (HDMI) were inactive. Forced to reboot PC to fully awaken. This behavior occurs sporadically while other times PC fully awakens and display is normal. No pattern of consistency. Frustrating.

The 4-year old wireless keyboard/mouse combo is the normal configuration and was moved from the 6-year old PC (Dell 8700). All drivers are up to date. Moving USB unifying receiver to different ports resulted in no change.

Current configuration:

• Reset all power configuration plans to back to default.
• Reset hibernation back to default (on).
• Set power configuration to ‘High Performance’ (was balanced).

Conclusion:

It appears the wireless keyboard/mouse unifying USB receiver regardless of what port its plugged into, causes some issues with ports (specifically HDMI) when waking the PC up from a sleep state. Another (newer) wireless keyboard/mouse combo with a non-unifying USB receiver may produce different results.

New human behavior. Since the wireless keyboard/mouse combo suits my needs, I’ll have to awaken the PC using a momentary press of the PC power switch.

Special thanks for RoHe and Vik384 who took the time to help figure this out.

Glad you narrowed it down to the wireless keyboard. Still sounds like a hibernation issue.

Have you gone into Device Manager and changed the setting on the Power Management tab for any device listed either under USB and/or under Human Interface Devices with that PM tab so PC cannot turn it off?

As you can see by my previous post, no real solution found -- so far. Just a workaround.

If you mean by turn it off, under the power management tab, "Allow PC to turn off device to save power" should be unchecked.

Under Human Interface Devices group:

The 'Logitech USB Input Device' entry under the power management tab to save power WAS checked and now is unchecked. I'm guessing this is the USB receiver for the keyboard/mouse. Two other entries that read 'USB Input Device' were also checked and now are unchecked. As a result, no other devices or entries under this group have the 'save power' box checked.

Under Keyboard and Mouse devices, the option to save power is grayed out; the option 'Allow this device to wake...' is checked only on keyboard.

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@Mebe2003 wrote:

If you mean by turn it off, under the power management tab, "Allow PC to turn off device to save power" should be unchecked.

 

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That's exactly what I meant. Uncheck the box "Allow PC to turn off..." for all devices listed under USB and under Human Interface Devices in Device Manager that have that box on their Power Management tab, regardless of their description.

Also check the box to allow mouse to wake PC too, if it's available.

Reboot and see what happens now. And let us know if the problem is fixed when using the wireless keyboard and mouse.

All devices under Human Interface Devices that deal with saving power are unchecked. I would have thought setting power plan to High Performance would have done that. 

Starting PC from sleep state via keyboard only resulted in 1 (out of 4) successful events where monitor and screen were awakened. The other times as before, monitor remains on standby and have to reboot to restore all to normal.

So I've given up on using keyboard to awaken and will return to momentary PC power button press which was 100% successful.

Thanks again for your help, tips and suggestions.

@Mebe2003  Well, at least you have a work-around.

What version of BIOS is installed on this XPS 8940?