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PG32UCDM Auto-detect Input Bug

Level 7

I discovered a bug that seems to be related to the automatic input/source detection on the PG32UCDM monitor. In my setup, I have two monitors connected to my PC: the PG32UCDM and one other. They are both connected with HDMI. However, I often only enable one monitor at a time depending on what I'm working on (or gaming). Both screens are powered on, but the one disabled in Windows enters standby. When I'm only using the other monitor, the PG32UCDM seems to periodically scan for other active sources. When it does this, it must break the HDMI connection. When the PC detects that an HDMI connection was changed, it follows its normal process of detecting the new monitor configuration, setting window positions, scaling, etc. This causes the screen I'm using to go blank and then come back. However, since the PG32UCDM quickly switches back and forth between HDMI-1 and other potential inputs, the other monitor's HDMI signal is rapidly interrupted and restored. If this happens too much, the other monitor sees this as an input error and it will shut down until manually power cycled. This doesn't happen every time the PG32UCDM attempts to detect inputs, but it is very frequent. After the process completes, "HDMI-1 No Input" is briefly displayed on the PG32UCDM, even when it's still in standby and disabled from the PC.

Turning off the PG32UCDM entirely instead of letting it go to standby fixes the problem. Disabling the "auto-detect input" setting also resolves it, but the screen still seems to keep trying HDMI-1 and displaying the "No Input" message over and over. I'm worried this could eventually cause burn-in.

Before I figured out the cause of the problem, I tried the following to rule out other potential issues:

  • my PG32UCDM is on the latest 103 firmware
  • tested different GPUs
  • different ports, HDMI and DP, on both the screens and graphics card
  • different nvidia driver versions
  • the problem also happens when in the BIOS so it's not Windows-related
  • known working power supplies
  • multiple HDMI 2.1 cables, both copper and fiber, short and long
  • BIOS update, and resetting to defaults
  • disabling DSC, VRR, and HDR
  • running lower refresh rates like 60Hz
  • the proximity detection has been disabled

Below are my relevant system specs:

  • Asus TUF GAMING X570-PRO (WI-FI) motherboard
  • AMD 5950x
  • Asus nvidia 3080 12GB GPU
  • Corsair HX850 PSU (also tried an EVGA Titanium 850W)

Customer Service Agent

Hi @klaxian ,

thank you for contacting us. 

Based on your issue, we would like to confirm if your current problem is related to using the HDMI connection on both displays of the PG32UCDM. Specifically, is one of the displays set to standby mode, causing the PG32UCDM to continuously detect other input sources, resulting in a black screen on the active display and displaying the message "HDMI-1 No Input"?

Could you please let us know if both displays are PG32UCDM models? 

Additionally, have you enabled the Auto KVM function? Did the issue occur with previous firmware versions?

To further investigate your issue, could you please provide a video showing the problem occurring? 

We kindly request that you record the video in MP4 format, ensuring that both displays and wiring status are clearly visible.

Thank you.

Level 7

Thanks for looking into this. I'll do my best to answer your questions.

  • Yes, the issue only occurs when the PG32UCDM is set to standby mode because the display is disabled in the Nvidia control panel. I only enable one screen at a time because they are for different purposes and they are set up at different locations in my room.
  • My other screen is a MSI MPG 271QRX.
  • Yes, I am using HDMI 2.1 for both displays.
  • Again, the problem only happens when "auto-detect input" is enabled on the PG32UCDM and it's in standby while the other screen is enabled.
  • No the Auto KVM function is disabled.
  • I don't know if the issue happened with a previous firmware version. I've always used 103.
  • I have attached a video of the PG32UCDM while the problem occurs. As you can see, it just shows "HDMI-1 NO SIGNAL" off and on. This video is when "Auto-detect Input" is disabled and the screen is in standby. The other screen is not affected in this case. When "Auto-detect Input" is enabled, the same screen shows periodically on the PG32UCDM at the same time as the other screen flickers or goes blank, but it is less frequent. I can't show both screens in the same video because they are not near each other.
  • I attached photos of the wiring.

It seems to me that the PG32UCDM is potentially breaking the HDMI connection when scanning for other inputs. Windows behaves as if the cable is unplugged and then plugged back in quickly. This does not happen every time, but it happens at least once per hour. Sometimes it will cause problems requiring a system reboot to correct. It makes the computer unusable. As I mentioned, disabling "Auto-detect Input" on the PG32UCDM resolves the issue, but it still seems to constantly hunt for a signal and display the message shown in my video. Turning off the PG32UCDM fixes both issues. However, I would like to be able to let it run in standby when I'm using the other screen so I can easily switch between them when needed.


Customer Service Agent

Hi @klaxian ,

thank you for providing the information. 

Regarding the video, could you please zoom out the camera and capture the entire monitor (including the power indicator) displaying "HDMI-1 NO SIGNAL"? Could you also provide the video file in MP4 format for our reference? 

You mentioned that the two monitors are placed at a distance from each other. 

Could you please provide a detailed description of how you have connected the two monitors? 

Did you use any docking stations or other devices for the connection?

Additionally, may I ask if you encountered this issue right after purchasing the monitor, or did it occur after making any changes? 

Thank you.

Level 7

The power indicator is solid ORANGE (standby) when the screen is flashing "HDMI-1 NO SIGNAL". The only way to attach a video seems to be with an external link (ie. YouTube). If there is a way to attach an MP4 file to a post that I'm missing, please let me know.

The monitors are connected directly to my video card with HDMI 2.1 certified cables. No, I am not using any docking station, adapter, or anything between the video card and the screens. As I mentioned, I tried several different known working HDMI cables as well as DP, but it did not fix the problem. Each screen works fine when connected by itself, and I can work around the issue with the PG32UCDM by disabling "auto-detect input" (but the screen still flashes "HDMI-1 NO SIGNAL").

The issue has always been present, ever since I purchased the screen, but it took some time to figure out the cause.

You should be able to replicate the behavior on your end with a test. Connect a PG32UCDM and another screen to a computer with HDMI. Set the PG32UCDM to disabled using the nvidia control panel. The problem is more prevalent when using high-bandwidth features like 360Hz, HDR, and DSC, but it also happens at lower refresh rates with these disabled. Launch a game that will utilize HDR and high HDMI bandwidth. It should happen within an hour or so, and then repeatedly. To reiterate, using features like high refresh, HDR, DSC, VRR, and running a game seem to make the issue happen more often, but it also happens with all these disabled, even in the BIOS before Windows is loaded. I suspect that the connection is more sensitive to momentary resets when it's at the edge of it's capabilities.

Please let me know if there's anything else I can do to help. I suspect this will need to be fixed in a future firmware update.

Customer Service Agent

Hi @klaxian ,

thank you for the information. 

Regarding the MP4 video, when you post a message, you can attach a file in the red box. 

Please kindly provide the complete video of the issue occurring at the time. 

Thank you.