Your monitor is powered on and shows No Signal or No Input Detected while the computer appears to be running. This applies to external monitors over HDMI, DisplayPort, DVI, VGA, or USB-C on Windows and Mac setups.
Does This Affect You?
No Signal means the monitor is not receiving usable video on the input it is currently watching. The monitor itself is alive, so the usual causes are input selection, a loose cable, sleep state, wrong graphics port, or a display driver issue.
Check the Cable and Input Source
This fixes many No Signal cases.
- Unplug and firmly reseat the video cable at both the computer and monitor.
- Use the monitor Input or Source button to choose the exact port in use, such as HDMI 1, HDMI 2, DisplayPort, or VGA.
- Swap to another HDMI or DisplayPort cable if you have one.
- Try another output port on the computer, including another GPU port or a video-capable USB-C port.
Wake the Computer and Check Sleep Settings
A sleeping PC can leave a monitor with no signal.
- Move the mouse or press a key. If nothing happens, press the computer power button briefly to wake it.
- On a desktop, confirm fans or lights show the computer is actually running.
- On Windows, open power settings and increase screen or sleep timeout if the issue repeats.
- On Mac, check Lock Screen or display sleep timing.
Rule Out a Graphics Card or Resolution Problem
Use this if cables, input, and wake state look correct.
- On desktops with a dedicated GPU, plug the monitor into the graphics card ports, not the motherboard ports.
- Restart with the monitor on and connected. If startup appears but Windows disappears, suspect driver or resolution settings.
- After Windows has had time to load, press Windows+Ctrl+Shift+B to reset the display driver.
- If the issue began after a graphics driver update, roll it back in Device Manager if possible.
Test each half of the setup. Connect the monitor to another computer or console. If it works, the original PC is the issue. Connect another monitor or TV to the PC. If that works, the first monitor or cable is suspect.
A desktop graphics card that has shifted in its PCIe slot can also cause No Signal. Shut down, unplug power, ground yourself, remove and reseat the card, then reconnect its power cables. These steps are at your own risk; use repair support if unsure.
Sources
- Dell Support – Monitor displays No Signal message (2025)
- Microsoft Support – Fix screen resolution and display issues in Windows (2025)
- NVIDIA Support – No signal to monitor troubleshooting (2024)