Diagnosis
The "No HDMI Cable" message on your Dell S2425HSM indicates the monitor's firmware is not detecting a valid video signal from the connected source, causing it to enter its auto-standby mode. This is typically a handshake or signal detection issue, not necessarily a faulty cable. Common culprits are a loose connection, incorrect input source selected on the monitor, a source device that is asleep or outputting an unsupported resolution, or a temporary glitch in the communication between devices.
How to Fix It
- Power cycle the entire setup: Turn off the monitor and the computer (or game console). Unplug the HDMI cable from both ends, wait 30 seconds, then reconnect it firmly until it clicks.
- Power on the source device first, wait for it to fully boot, then turn on the monitor.
- Press the monitor's physical menu button to open the On-Screen Display (OSD). Navigate to Menu > Input Source and manually select HDMI, even if it appears selected.
- On your computer, ensure the display is not set to duplicate or extend to an incorrect display. In Windows, press Win+P and select "PC screen only" or "Duplicate."
If That Didn't Work
Test with a different, known-working HDMI cable (preferably a high-speed one). Try a different HDMI port on your computer or GPU if available. If you have another device (like a laptop or gaming console), connect it to the monitor to isolate the fault. Finally, perform a factory reset on the monitor via the OSD (Menu > Others > Factory Reset).
Heads Up
The Dell S2425HSM will automatically enter standby after approximately 4 minutes of receiving no signal, which is normal behavior. If the problem only occurs with a specific device, check that device's graphics drivers and ensure it's set to output a resolution and refresh rate (like 1920x1080 at 144Hz) supported by the monitor.