Self HelpBoise Computer Care

Windows

Second monitor not detected

Second monitor not detected in Windows? Check input, cables, Windows+P, Detect, driver reset and USB-C video support, step by step.

Difficulty
Easy
Time
10-20 min
Steps
8
Updated

Sounds like this?

  • External monitor says 'No signal'
  • Only one screen shows in Display settings
  • Monitor worked before a driver update
  • Dock or USB-C display not working

Step by step

  1. Check the monitor's input: use its buttons to select the correct input (HDMI 1, HDMI 2, DisplayPort).
  2. Reseat both ends of the cable. Try a different cable and a different port if you have one.
  3. On a desktop with a graphics card, plug the monitor into the card's ports (lower, horizontal ones), not the motherboard ports.
  4. Press Windows + P and choose Extend.
  5. Go to Settings › System › Display › Multiple displays › Detect.
  6. Press Windows + Ctrl + Shift + B to reset the graphics driver (the screen blinks once).
  7. Update the graphics driver from Intel, AMD, or NVIDIA, or your laptop maker's support page.
  8. For USB-C, confirm the port supports video (DisplayPort or Thunderbolt symbol). Not every USB-C port does. Docks may need their own driver (for example DisplayLink).

Related error codes & messages

Quick answers

When should I stop and get professional help with "Second monitor not detected"?

Stop and get help if: The monitor shows nothing even on another computer: the monitor or its power supply may be bad. The port on the laptop is loose or bent. Lines, flicker or color bars appear on every screen (possible GPU failure). Boise Computer Care can diagnose it for a $60 fee; call 208-996-3508.

How long does this fix take and how hard is it?

Plan on 10-20 min. Difficulty: Easy.

Is it safe to try this myself?

Mostly, if you follow these precautions: Turn off and unplug the monitor before reseating cables on desktops.

Which error messages or codes does this guide cover?

No signal, Input not supported, Code 43.

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