Hi everyone, I’m having an issue with my Samsung LS24DG30X monitor when using DisplayPort, and I’d like to share all the tests I’ve done so far to see if anyone has suggestions or if this is a known problem.
Problem Description
When Windows turns off the display after inactivity, the LS24DG30X does not enter standby while connected via DisplayPort. Instead, it stays powered on with a black screen and sometimes switches repeatedly between HDMI and DP inputs.
If I disconnect the DP cable physically, the monitor immediately enters standby, so the monitor can go to sleep, but it doesn’t do it when the PC stops sending a signal.
My second monitor (ViewSonic XG2705‑2K), connected to the same GPU via DP, enters standby normally, so the issue is isolated to the Samsung.
Tests I Have Done
1. Tested multiple DisplayPort ports on the GPU
Tried DP port 2 and DP port 3
Result: No change
2. Tested multiple DisplayPort cables
Original Samsung DP cable
ViewSonic DP cable
Result: No change — Samsung still won’t enter standby via DP
3. Tested HDMI
When connected via HDMI, the monitor enters standby correctly
But HDMI does not support VRR on this model, so DP is required
4. Full GPU driver cleanup with DDU
Booted into Safe Mode
Used DDU to remove all NVIDIA drivers
Blocked Windows Update from reinstalling drivers
Installed NVIDIA driver 591.59 cleanly
Result: No change
5. Reset the monitor to factory settings
Full OSD reset
Result: No change
6. Tested monitor power‑saving features
Off Timer Plus (set to 1 hour)
Works as a fixed timer, but does not react to Windows turning off the display
Eco Timer (set to 10 minutes)
Only triggers if the monitor detects no signal
Since the Samsung still receives a “black” DP signal, Eco Timer does not activate
7. Physical DP cable disconnect test
If I unplug the DP cable, the monitor immediately enters standby
Confirms the monitor can sleep, but does not detect the loss of DP signal properly
OSD Settings Verified
Auto Source Switch: Off
DisplayPort Version: 1.2
FreeSync: On
Eco Saving Plus: Tested
Off Timer Plus: Tested
Eco Timer: Tested
Picture Mode: Custom
Conclusion
Everything points to a firmware issue with how the LS24DG30X handles DisplayPort signal loss. The GPU, drivers, cables, and Windows settings are all functioning correctly.
The monitor:
Works in HDMI
Works in DP when showing an image
Fails only when Windows turns off the display via DP
