Monitor Says “No Signal”: Causes and What to Do

Monitor Says “No Signal”: Causes and What to Do

The No Signal, No Input Signal, Signal Not Found, or Check Signal Cable message means that the monitor is powered on but is not receiving a video signal from the computer, laptop, or another connected device.

This does not necessarily mean that the monitor itself is faulty. The problem may be caused by an incorrect input source, an HDMI or DisplayPort cable, the computer's video output, the graphics card, or Windows settings.

It is best to troubleshoot the problem step by step, starting with the simplest causes before moving on to possible hardware faults.

Check the Monitor Input Source

Modern monitors often have several video inputs:

• HDMI 1 and HDMI 2;
• DisplayPort;
• USB-C;
• DVI or VGA on older models.

For example, if your computer is connected via HDMI but DisplayPort is selected in the monitor settings, the screen may display No Signal.

Open the monitor menu, find Input, Input Source, or Source, and select the port to which the cable is actually connected.

Even if the monitor supports automatic input detection, selecting the correct input manually is a good troubleshooting step.

Check the HDMI or DisplayPort Cable

Turn off the computer and monitor, then reconnect the video cable at both ends.

Make sure the connectors are fully inserted. Pay particular attention to DisplayPort connections — sometimes the cable may appear to be connected even when it is not fully seated.

If there is still no signal, try:

• another known-good HDMI or DisplayPort cable;
• another video input on the monitor;
• another video output on the computer.

If you are using an adapter or docking station, temporarily remove it from the connection and, if possible, connect the monitor directly.

Check Where the Monitor Is Connected on a Desktop PC

If your desktop PC has a dedicated graphics card, there may be HDMI and DisplayPort connectors on both the motherboard and the graphics card.

The monitor should normally be connected directly to the dedicated graphics card.

If the cable is connected to the motherboard while the processor has no integrated graphics or the integrated graphics is disabled, the monitor may display No Signal.

This is especially common after moving a computer or reconnecting its cables.

Connect the Monitor to Another Device

One of the easiest ways to determine where the problem is located is to test the monitor with another video source.

You can connect it to:

• another computer;
• a laptop;
• a game console;
• another compatible device.

If the monitor displays an image with another device, the monitor and the video input you tested are most likely working correctly. In this case, the problem should be investigated on the original computer, its video output, or its settings.

You can also perform the opposite test by connecting the computer to another monitor or TV.

These cross-checks can often identify the source of the problem much faster than reinstalling drivers or randomly changing settings.

If No Signal Appears After Windows Starts

Pay attention to exactly when the image disappears.

If you can see the manufacturer's logo or BIOS during startup, but the monitor displays No Signal after Windows loads, the cause may be software-related.

Check:

• the graphics card driver;
• display resolution;
• refresh rate;
• multiple-display settings;
• recent Windows or GPU driver updates.

In Windows, display settings can be found under:

Settings → System → Display → Advanced display

You can also try pressing:

Win + Ctrl + Shift + B

This restarts the Windows graphics driver. The screen may briefly flicker during the process.

If there is no image even during computer startup or when entering BIOS, the problem is unlikely to be caused by a Windows driver.

If No Signal Appears When Connecting a Monitor to a Laptop

If an external monitor is connected to a laptop, press:

Win + P

And check the available display modes:

• PC screen only;
• Duplicate;
• Extend;
• Second screen only.

You can also open:

Settings → System → Display

And check whether Windows detects the external monitor.

USB-C connections require some additional attention. The presence of a USB-C port does not automatically mean that it supports video output. The port must support an appropriate video output function, such as DisplayPort Alt Mode, if that is required for the connection being used.

Can No Signal Be Caused by the Graphics Card or Computer?

Yes. The No Signal message only means that the monitor is not receiving a video signal. It does not identify which device is faulty.

If the computer does not display an image on any known-good monitor, possible causes include:

• graphics card;
• RAM;
• motherboard;
• power supply;
• another hardware problem preventing the computer from completing its initial startup.

If you cannot even see the BIOS or startup logo, reinstalling the graphics driver will not solve this type of problem.

When Could the Monitor Itself Be the Problem?

The monitor can also be responsible for a No Signal message.

Possible faults include:

• HDMI or DisplayPort input;
• the physical connector;
• video signal processing board;
• internal connections or other components.

For example, if HDMI 1 does not receive a signal from several known-good devices and cables, while HDMI 2 works normally, the first input may be faulty.

If the monitor does not receive a signal through any input from several tested devices, it should be professionally diagnosed.

What You Can Check Yourself

If your monitor says No Signal, check the following in order:

1. Make sure the monitor is powered on and its on-screen menu opens.
2. Select the correct Input Source.
3. Reconnect the HDMI or DisplayPort cable.
4. Try another known-good cable.
5. Try another video input.
6. On a desktop PC, make sure the cable is connected to the correct video output.
7. Connect the monitor to another device.
8. If the signal disappears after Windows starts, check the graphics driver, resolution, and refresh rate.

These steps are usually enough to determine which side of the connection is causing the problem.

When Is Professional Diagnostics Needed?

Consider contacting a service center if:

• the monitor constantly displays No Signal with different known-good cables;
• several video sources have been tested but no image appears;
• an HDMI or DisplayPort input does not work;
• the connector is physically damaged;
• the signal appears only when the cable is moved or held in a certain position;
• the computer does not output an image to any known-good display.

During diagnostics, it is important to first determine which device is actually faulty — the monitor, computer, laptop, graphics card, or another component in the connection.

Conclusion

A No Signal message does not automatically mean that the monitor is broken. It simply means that the display is not receiving a video signal.

Start with the basic checks: select the correct HDMI or DisplayPort input, reconnect the cable, and try another port. Then test the monitor with another device.

If the image is visible before Windows starts but disappears afterward, check the graphics driver and display settings. If the monitor does not receive a signal from several known-good devices using different inputs and cables, the problem may be with the monitor itself.