A monitor showing No Signal means the display receives power but detects no video input, and the most common cause is the wrong input source selected on the monitor. Other frequent causes include a cable plugged into the motherboard instead of the graphics card, a dead or loose video cable, a graphics card that is not seated or has no power, the monitor sitting in standby, a resolution the monitor cannot display, and a failed graphics card. This article explains what causes a No Signal message and gives the step-by-step fixes that restore the image.
Each fix names the exact action to take, including selecting the monitor input source, using the graphics card ports, swapping the cable, and reseating the card. The fixes are ordered from the most common and easiest, such as choosing the right input, to reseating hardware. This guide covers a monitor that reports No Signal while the computer is on, which differs from a whole-system failure where the computer powers on with no display at all.
What Causes a Monitor to Show No Signal?
A monitor shows No Signal when it powers on but receives no video data over the connected cable, so it reports an empty input. The causes below are ranked from most to least common.
- The wrong monitor input source. The monitor is set to an input, such as HDMI 1, that has no cable, while the active cable sits on a different input.
- The cable plugged into the motherboard. On a desktop with a graphics card, a cable in the motherboard ports sends no signal when the integrated graphics is inactive.
- A dead or loose video cable. A failed or half-seated HDMI or DisplayPort cable carries no image.
- A graphics card not seated or without power. A card that has shifted in its slot or lacks its PCIe power connectors produces no output.
- The monitor in standby. A monitor that never leaves standby shows No Signal and then a blank screen.
- A resolution mismatch. A resolution or refresh rate the monitor cannot display leaves the screen blank after Windows loads.
- A failed graphics card. A defective card outputs nothing on any port.
Set the Monitor Input Source
Selecting the input that matches the connected cable resolves the most common cause of a No Signal message. Each monitor has a Source or Input button that cycles through its connectors.
- Press the Source, Input, or Menu button on the monitor.
- Cycle through the listed inputs, such as HDMI 1, HDMI 2, and DisplayPort.
- Select the input that matches the cable plugged into the monitor.
- Wait a few seconds after each selection for the monitor to detect the signal.
- Set the monitor to Auto Source if available so it finds the active input on its own.
A monitor with several inputs defaults to one connector and reports No Signal on the others, so matching the input to the cable is the first check.
Plug Into the Graphics Card, Not the Motherboard
Connecting the cable to the graphics card ports rather than the motherboard restores the image on a desktop that has a dedicated graphics card. A dedicated card disables the motherboard video output by default.
- Locate the horizontal ports lower on the rear of the desktop, which belong to the graphics card.
- Identify the vertical ports near the top, which belong to the motherboard.
- Move the cable from the motherboard ports to the graphics card ports.
- Use a DisplayPort or HDMI port on the graphics card that matches the cable.
- Power on and confirm the monitor detects the signal from the card.
A cable in the motherboard ports shows No Signal whenever a dedicated graphics card is installed and the integrated graphics output is inactive. The difference between port types is detailed in the guide to types of computer ports.
Swap the Cable and Try a Different Port
Replacing the video cable and using a different port rules out a dead cable or a faulty connector as the cause. HDMI and DisplayPort cables fail without visible damage.
- Reseat the existing cable firmly at both the monitor and the computer ends.
- Replace the cable with a known-good HDMI or DisplayPort cable.
- Move the cable to a different port on the graphics card.
- Match the cable to the port type, because a DisplayPort cable does not fit an HDMI port.
- Power on and confirm the monitor detects the new connection.
A monitor that detects a signal on a new cable or port confirms the original cable or connector was the fault.
Reseat the Graphics Card and PCIe Power
Reseating the graphics card and reconnecting its PCIe power cables restores output when the card has shifted in its slot or lost power. A card that is not fully seated produces no signal on any port.
- Power off the computer and unplug it from the wall.
- Open the case and release the PCIe slot latch holding the graphics card.
- Remove the card, then press it firmly back into the slot until the latch clicks.
- Reconnect every PCIe power cable from the power supply to the card.
- Confirm any power-indicator light on the card is lit before closing the case.
A graphics card that draws too much power from a marginal supply also fails to output an image. A whole-system failure where the computer powers on with no display at all is covered in the guide to a PC that turns on with no display.
Test Another Monitor or Cable
Connecting a second monitor or a different cable confirms whether the fault sits in the monitor, the cable, or the computer. Substitution isolates the failing part.
- Connect a known-working monitor to the same computer with a known-good cable.
- Confirm the second monitor detects a signal, which clears the computer of fault.
- Connect the original monitor to a different computer or device.
- Confirm the original monitor displays an image from that source, which clears the monitor.
- Replace whichever part fails to produce an image during the substitution test.
A monitor that works on another computer but not the original points to the graphics card or its connection rather than the monitor itself.
Boot to Safe Mode for a Bad Resolution
Booting into Safe Mode loads Windows at a basic resolution so a display setting that exceeds the monitor capability can be corrected. A wrong resolution or refresh rate leaves the screen blank only after Windows loads.
- Force three failed boots by powering off during the Windows logo to trigger the Windows Recovery Environment.
- Select Troubleshoot, then Advanced options, then Startup Settings, and restart.
- Press the key for Enable low-resolution video or Safe Mode.
- Open Display settings and set a resolution and refresh rate the monitor supports.
- Restart normally and confirm the image holds.
A screen that shows the BIOS and the Windows logo but goes blank after loading points to a resolution or refresh-rate setting rather than a hardware fault. The supported refresh rates for a display are explained in the guide to monitor refresh rate.
Check Monitor Power and Standby
Confirming the monitor has power and is not stuck in standby rules out the display itself as the reason for a blank screen. A monitor in standby shows No Signal and then darkens.
- Confirm the monitor power light is on and not blinking in a standby pattern.
- Reseat the monitor power cable at both the monitor and the wall outlet.
- Press the monitor power button to wake it from standby.
- Open the on-screen menu to confirm the monitor responds, which proves it has power.
- Test the monitor on a different power outlet if the light stays off.
A monitor whose on-screen menu opens has power and an active panel, so a blank screen with a working menu points to the input or the source rather than the display.
Monitor No Signal: Symptoms and Causes
| Symptom | Likely Cause | First Fix to Try |
|---|---|---|
| No Signal on one input only | Wrong input source selected | Select the matching input source |
| No Signal on a desktop with a GPU | Cable in the motherboard ports | Plug into the graphics card ports |
| Blank screen after Windows loads | Resolution or refresh rate mismatch | Boot Safe Mode and lower the resolution |
| No Signal on every port | Graphics card unseated or no power | Reseat the card and PCIe power |
| Monitor light blinks, screen dark | Monitor stuck in standby | Reseat power, wake the monitor |
| No image on any computer | Failed monitor | Replace the monitor |
Key Takeaways
- Select the right input first. The wrong input source is the most common cause of a monitor showing No Signal.
- Plug into the graphics card. A desktop with a dedicated card needs the cable in the card ports, not the motherboard.
- Swap the cable and port. A dead HDMI or DisplayPort cable carries no image and fails without visible damage.
- Reseat the graphics card. Reconnect the card in its slot and its PCIe power cables when no port outputs.
- Use Safe Mode for resolution faults. A blank screen only after Windows loads points to a wrong resolution.
Why does my monitor say No Signal when my PC is on?
The monitor receives no video input. The most common cause is the wrong input source selected on the monitor. Press the Source button and choose the input that matches the connected cable.
Why is my monitor saying No Signal with a graphics card installed?
The cable is likely plugged into the motherboard ports. A dedicated graphics card disables the motherboard video output. Move the cable to the graphics card ports lower on the rear of the desktop.
How do I fix a No Signal message on my monitor?
Select the correct input source, plug the cable into the graphics card, swap the cable and port, reseat the graphics card with its PCIe power, and test another monitor to isolate the failing part.
Can a bad cable cause No Signal?
Yes. An HDMI or DisplayPort cable can fail without visible damage and carry no image. Reseat the cable at both ends, then replace it with a known-good cable and confirm the monitor detects the signal.
Why does my screen go blank after the Windows logo?
A resolution or refresh rate the monitor cannot display leaves the screen blank after Windows loads. Boot into Safe Mode or low-resolution video and set a supported resolution in Display settings.
Is No Signal a monitor or computer problem?
Test a second monitor on the computer and the original monitor on another device. If the second monitor works, the fault is the cable or graphics card. If the original works elsewhere, the computer is at fault.
Last Thoughts on a Monitor Showing No Signal
A monitor showing No Signal is resolved by matching the input source to the cable, connecting to the graphics card instead of the motherboard, and reseating the cable or card when no port outputs an image. The wrong input and a motherboard-connected cable account for most cases on a desktop with a dedicated graphics card.
A No Signal message differs from a system that never reaches the display, which the guide to a PC that turns on with no display addresses. When the image appears and then flickers or drops, the steps to fix screen flickering and to fix a second monitor not detected apply, and a full index of display faults sits in the hub of common PC problems.
