Symptoms
- Monitor shows no signal or stays black
- No Windows logo, login screen, or cursor appears
- Fans and lights on the PC still turn on
- Sometimes accompanied by beeping sounds
Likely causes
- CommonLoose or faulty display cable/connectionA cable that's slightly unseated can produce a completely blank screen.
- CommonMonitor set to wrong input sourceEasy to overlook, especially after moving cables.
- PossibleGraphics card or onboard GPU not seated or failingA dislodged card after moving the PC is a frequent cause.
- PossibleWindows failing before reaching the login screenA boot failure can leave the screen dark rather than showing an error.
- Less commonFailing power supply or motherboardInsufficient or unstable power can prevent video output entirely.
What to do
- Confirm the monitor is on and set to the correct input (HDMI, DisplayPort, etc.), cycling through inputs with its menu button.
- Reseat the video cable at both ends, and try a different cable or port if you have one.
- Listen for beep codes from the PC speaker; a pattern of beeps points to a specific hardware problem you can look up for your motherboard brand.
- For desktops, open the case and reseat the graphics card and RAM sticks by removing and firmly reinserting them.
- Try connecting the monitor to a different port (for example, the motherboard's onboard video instead of a graphics card) to isolate which component is at fault.
- If you have a spare monitor or cable, swap it in to rule out a monitor or cable failure.
- If there's still no video output on any port with known-good cables, the graphics card, motherboard, or power supply likely needs professional diagnosis.
Tools and parts
- Spare HDMI or DisplayPort cable if available
When to call a pro
If reseating cables and components doesn't restore video and beep codes point to hardware failure, a repair shop can test the graphics card, RAM, and power supply individually.
Safety
Use caution
Unplug the PC from the wall before opening the case or touching internal components.