Monitor won't stay off in sleep mode

[msimmons99]

My 27" FT45 monitor (LF27T450FQNXGO) goes into sleep mode and wakes up when it's supposed to. But while in sleep mode it will repeatedly turn on for a few seconds and back off. Continuously and regularly maybe every 10 seconds. What's on the screen is just what it was when it went to sleep; nothing changes there.

What's turning it back on? I've been turning the power off to make it stop at night or it will do this all night.

Thanks!

[orlum]

Same issue here with my new Odyssey G40. Connected HDMI to HDMI.

LS27BG400ELXZD - Firmware version M-B4000GCZA-1003.0 - Driver Version 1.0.0.0

Asus ROG Zephyrus S GX701GXR.310 -  Windows 11 Pro 2022H2 22621.1992

Intel UHD Graphics 360 - Driver version 31.0.101.2115

NVIDIA GeForce RTX 2080 With Max-Q - Driver version 31.0.15.3640

[Mtstewd]

Bought a LC49RG90SSNXZA, which is the 49 inch curved monitor, brand new. I have a Mac Studio, connected with a DisplayPort to USB Type C cable. Also a separate 10 year old LG monitor connected by HDMI. The Samsung will turn on randomly for a few seconds and off again. With absolutely no input from anyone, even the computer. The LG does not turn on. So what’s the solution again?

[gizmo77]

I bought a Samsung Odyssey G7 28" (LS28BG700) a couple weeks ago and when the screen goes into sleep mode, if I move the mouse to exit sleep mode, the screen turns on but it just displays the screen saying that there is no signal. turning off and on the screen won't help, I have to restart the computer. Disconnecting the cable would probably work, didn't try.

Configuration:

Windows 10 19045.3208
Nvidia 2080ti with drivers updated to v536.67
connected in displayport with a cable provided with the screen and tested with another 8k cable (32gb/s)
screen software updated v1444
set in 120hz in the Nvidia configuration panel but had the same problem when it was set in 144hz

[howardc64]

Ditto, for me is S60UA with USB-C charger and video connection to MacBook (MB) M1. But research shows it happens on many Samsung monitors.

The issue seems to be as follows

- Monitor goes into standby when I put MB to sleep. Monitor USB-C port remain charing the MB

- After a min or so, Monitor USB-C port will shut off power. This wakes up the MB enough for the Monitor to think there is a video connection. But no valid video signal so Monitor wakes up and goes back to standby

- Once this wakeup behavior starts, it just repeats for ever.

Here is someone that did detail analysis on macOS events to determine this

MacBook Pro M1 wakes due to USB-C chargin… - Apple Community

Reading other threads. Problem seems to show on USB-C and DP. I think the main issue is the monitor's HUB. For USB-C, it will cut the charging power (My Dell USB-C monitor doesn't do this and therefore don't have this issue) This is what prompts MB to wake up and then trigger screen to wake up. Don't know what is happening on DP but DP probably have bi-directional communication and monitor is probably triggering some event during standby at the same time as USB-C power gets turned off.

I also randomly see USB Accessory Disabled. I have no USB connection other than USB-C to the monitor so presumably HUB powering off is also powering off the USB devices on it (1x USB 2.1 HUB, 1x USB 2.0 HUB, 1x USB 3.2 HUB,  LAN) prompting MB to see the devices as disabled.

Most likely require firmware update but its been 2+ years already since product release without any firmware updates.

Called support and opened a tix but appears just a path way for return for service or refund. No pathway to support engineering.

BTW, sounds like Lenovo USB-C monitors is also having issues but different (doesn't charge reliably) with single USB-C cable operation.

[howardc64]

I believe I found a solution.  Here is a quick summary followed by more details

Basic Summary

• USB-C while look simple has a complex communication protocol over the wires for various transfers. For video display, it uses USB-C DP mode (Display Port Mode) Presumably this borrows transport specification from Display Port port protocol.
• Display Port is more complex than HDMI. So this issue will occur on USB-C and DP video connection but not HDMI.
• When macOS (don't know if only on newer macOSs)  is connected to external monitor with USB-C DP mode and Display Port. macOS will frequently wake up from USB events. These events are what is causing some monitors (Samsungs and LGs USB-C monitors) to frequently wake from standby, turn on backlight, detect no video signal, then back to standby... and repeat...
• Found a fairly senior poster said work around is... just don't sleep when external display is turned off and connected to AC (USB-C is providing power to charge+run the mac) On macOS ventura, its a simple switch under System Preferences->Display->Advanced. Turning this on worked for my M1 MBP on macOS Ventura.
• 
• BUT isn't not sleeping while turning off display a problem? It seems M1 may not be a problem as its so energy efficient like iPhones and iPads (Sounds like iPhones/iPads don't go to sleep when display is turned off). The concept of traditional computer sleeping to save power seems to no longer make sense with M1s

So I believe this solution works. Love to see more statistics from others using it.

Detailed Info

Run the following command line on a terminal to see the sleep wake events

pmset -g log | grep -e "Wake from" -e "Dark Wake" -e "Entering Sleep"

Before I turn on "don't sleep when display is off while on AC", I got the following from this command. Afterwards, I got no more sleep/wake events AND my Samsung S60UA stays dark and quiet until I wake it up.

2023-08-10 14:11:25 -0700 DarkWake            DarkWake from Deep Idle [CDNP] : due to ATC0.USBWakeup/ Using AC (Charge:80%) 45 secs   

2023-08-10 14:12:10 -0700 Sleep               Entering Sleep state due to 'Maintenance Sleep':TCPKeepAlive=active Using AC (Charge:80%) 681 secs 

2023-08-10 14:23:31 -0700 DarkWake            DarkWake from Deep Idle [CDNPB] : due to SMC.OutboxNotEmpty smc.70070000 wifibt wlan/ Using AC (Charge:80%) 187 secs 

2023-08-10 14:26:38 -0700 Sleep               Entering Sleep state due to 'Maintenance Sleep':TCPKeepAlive=active Using AC (Charge:80%) 1058 secs

2023-08-10 14:44:16 -0700 DarkWake            DarkWake from Deep Idle [CDNPB] : due to NUB.SPMI0Sw3IRQ nub-spmi.0x02 rtc/SleepService Using AC (Charge:80%) 44 secs   

2023-08-10 14:45:00 -0700 Sleep               Entering Sleep state due to 'Sleep Service Back to Sleep':TCPKeepAlive=active Using AC (Charge:80%) 19 secs   

2023-08-10 14:45:19 -0700 DarkWake            DarkWake from Deep Idle [CDNPB] : due to ATC0.USBWakeup/ Using AC (Charge:80%) 19 secs   

2023-08-10 14:45:38 -0700 Wake                DarkWake to FullWake from Deep Idle [CDNVA] : due to UserActivity Assertion Using AC (Charge:80%)

Here is the senior person that proposed this solution in reply to this thread. The poster thought this was a poor suggestion but I think the solution might be correct. Will need to use it for awhile and see what the energy consumption profile is while display is turned off.

Mac Mini M1 wakes from sleep - Apple Community

If you google "NUB.SPMI0Sw3IRQ", you will find many MBs reporting using up all the battery while closing the screen to sleep overnight. This is one of the events that wakes up the Mac in above event listing. In my current usage mode (MBP M1 clam shell closed, USB-C monitor providing power and display) This is probably not a problem. Just need to study more on what the power consumption is when sleep is disabled.

[BenignCosmicEntity]

This is a different issue to what I'm experiencing (on Viewfinity 34 inch S34C502GAN connected via DisplayPort to a USB-C dock which is connected to an M2 MacBook Pro), most notably because it still occurs when the MacBook is shut down and connected to the dock.

After reading your post I plugged the DP back in to check, and no wake events are recorded while the issue is occurring. Toggling the automatic sleeping option also has no effect.

[howardc64]

Yeah, you have a more complex setup for sure with S34C502GAN <-> DP <-> USB-C dock <-> M2. Curious if problem occurs if

- S34C502GAN <-> DP <-> USB-C dock without plugging in M2 (rather than just shutdown M2 and leave plugged into USB-C)

Does dock have HDMI? Maybe HDMI between monitor <-> dock might fix the problem? But maybe lose some desired capabilities? (high res at high frame rate?)

One way to think about it is your USB-C dock is my M1 so monitor <-> USB-C/DP and its sleep/wake communication is the cause. In your case, can't snoop the dock's sleep/wake behavior.

[msimmons99]

I've seen a few different setups that seem to have the same problem. In my case, it's on a Windows machine with the monitor connected via HDMI.

So it seems that there are different solutions in different situations but that they don't necessarily work in others.

The real solution should come from Samsung but I started this thread six months ago and even a moderator was unsuccessful at contacting them.

[howardc64]

There are pins on HDMI and DP (I assume also USB-C since it uses DP Mode for video) for hot plug detection. Basically its a way for both side of the connection to know if connection has been plugged/unplugged.

Hot Plug Detection, DDC, and EDID (datapro.net)

Lots of post on combination of PC and Monitor setups where monitor power off/sleep causes the PC to readjust its windows as the monitor triggers unplugged event which PC thinks the monitor has been removed.

Don't know if this is related to this class of problems we are seeing. Probably require someone with HDMI/DP signal analyzer box to snoop what is going on to understand further.

[idcha0s]

Let me start by saying that I love the VRR performance on my G8 OLED. The colors are amazing, and it performs extremely well during gaming. However, when I'm not gaming, and just using the PC, it's a HORRIBLE experience. Prior to swapping out my dual Dell 34" Ultra WQHD monitors for the new G8 OLED's, I had no issues with the PC's resuming from sleep mode, OR just from monitor idle power modes. What I do know if that if my computer does go to sleep, I will have to completely power it down to get it to come back - the monitors simply will not resume from sleep mode. There are cases where I have to take a 3rd 1080p monitor just to get the machine to boot before I can plug the G8's back in. What gives?

This is Windows 10 64bit, on all the latest patch/CU, with the Nvidia RTX 3070 running the latest Game Ready drivers. This has been going on for the past 2-3 months, ever since receiving the pair. I'm running two G8 OLED's in the native 3440x1440 resolution in "extended" multiple-display mode. I've tried disabling Game Mode and VRR and running in lower refresh rates but still the same issues resuming from sleep. I've also tried different HDMI-CEC settings, disabling power savings, etc. 

As near as I can tell, it correlates most often when the PC:
1) puts the monitor to sleep when in idle mode (Screen: When plugged in, turn off after n minutes)

2) PC decides to go to sleep (When plugged in, PC goes to sleep after n minutes)

The PC will resume from idle and turn the screens back on; however, all positional alignment of windows on the desktop are lost and I have to move them back to their previous coordinates. If the PC goes to sleep during this time the PC will wake, but I only get black screens and no video, even after a power cycle I often have to power the PC all the way down.

If I manually put the PC to sleep, it will wake up no problem, I only seem to get the black screens if both power downs have happened. Also curiously, I'm hoping the most recent 1440 firmware update fixes a separate black screen problem which happens during operation, most often when I'm focused on the other monitor, the non active monitor will black out and return 5 seconds later.

Puzzled...