Symptoms
- Screen shows 'No Signal' or 'No Input'
- Monitor power light is on (often amber or blinking)
- Screen was fine yesterday, black today
- Happens right after waking the computer
Likely causes
- CommonVideo cable loose or unpluggedCables work loose from vibration or cleaning; check both ends.
- CommonMonitor set to wrong input sourceMany monitors default to the last-used input, which may not be the connected one.
- CommonComputer is asleep or offA sleeping PC sends no signal even though the monitor is powered.
- PossibleFaulty or damaged cableBent HDMI/DisplayPort pins or a pinched cable can break the signal.
- Less commonGraphics card not seated or failingA loose GPU or driver crash can stop video output entirely.
What to do
- Wiggle and reseat the video cable at both the monitor and the computer end.
- Press the monitor's Input/Source button and cycle through HDMI, DisplayPort, and VGA options.
- Move the mouse or press a key to wake the computer, and check if the PC's power light and fans are on.
- Try a different video cable if you have one, ideally a known-good one from another device.
- If using a desktop, confirm the cable is plugged into the graphics card port, not the motherboard port, when a dedicated GPU is installed.
- Test the monitor on a different computer or laptop, and test your computer on a different monitor if possible.
- If nothing shows on any monitor, listen for the computer completing its normal startup beeps or fan ramp-up, which suggests a display-output rather than power problem.
Tools and parts
- None, or a spare video cable
HDMI or DisplayPort cableSearch: “HDMI 2.0 cable 6ft”
When to call a pro
If the computer powers on normally but no monitor anywhere shows an image, have a computer repair shop check the graphics card and motherboard.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.