Adding a second screen is a great productivity boost, that is until it suddenly decides to stop working. Whether your monitor shows “No Signal”, flickers, or stays black, the cause is often something you can fix yourself. Here are some quick checks to get your display back up and running before you have to call IT.
1. Check the Basics First
It might sound obvious, but loose connections are the most common reason a monitor won’t display. Make sure:
- The cable is securely plugged into both the monitor and your computer.
- The monitor is powered on (watch for a power light).
- You’re using the right input source (HDMI, DisplayPort, VGA, etc.) depending on your cable
If your monitor has multiple input ports, use the Input/Source button to toggle through options. You might simply be on the wrong one.
2. Try a Different Cable or Port
Cables wear out, especially if they’re plugged and unplugged often. If you have a spare HDMI or DisplayPort cable, swap it in. If your computer has multiple display ports, try another one.
Keep in mind that not all USB-C ports support video output, some only handle charging or data transfer. Look for a small DisplayPort (⎔) or lightning bolt (⚡) icon next to the port, which indicates it supports display. If you’re using a desktop computer with a dedicated graphics card, make sure your display cable is plugged directly into the GPU’s ports, not the ones on the motherboard. Connecting to the wrong set of ports can prevent your monitor from showing anything at all.
Pro tip: If the second port works, the issue is most likely with the port itself. Make a note of it before calling support.
3. Detect the Display Manually
Sometimes your computer doesn’t automatically recognize a new monitor. Here’s how to prompt it:
- On Windows: Go to Settings > System > Display > Multiple displays and click Detect.
- On macOS: Go to System Settings > Displays and click Detect Displays while holding the Option key.
If the monitor appears after this, select Extend or Duplicate display mode, depending on your preference.
4. Check Display Settings
If your screen appears but stays black or blurry, your resolution might be set too high or routed to the wrong display.
- Lower the resolution under Display Settings to see if the monitor lights up.
- On laptops, try pressing Windows + P (or Command + F1 on Mac) to toggle between display modes.
Pro tip: Rebooting the computer and power-cycling the monitor (unplug for 10 seconds, then plug it back in) can also clear small connection hiccups!
5. Update Yours Graphics Driver
Outdated or corrupted graphics drivers are one of the most common reasons external monitors won’t display correctly. Drivers act as the translator between your computer’s hardware and the operating system. If they’re out of date, your system might not know how to communicate with your graphics card correctly.
Here’s how to check for updates:
- On Windows:
- Open Device Manager (search for it in the Start Menu).
- Expand Display adapters and right-click your graphics card.
- Select Update driver > Search automatically for drivers.
- If Windows doesn’t find an update, visit your computer manufacturer’s website (like Lenovo, HP, Dell, ASUS, etc.) and download the latest graphics driver for your model, or check to see if there’s a preinstalled app for driver updates.
- Tip: If you have a dedicated graphics card from NVIDIA, AMD, or Intel, download their driver update tool from their official website for the most reliable version.
- On macOS:
- Graphics drivers are included with macOS updates, so running System Settings > General > Software Update ensures your display drivers stay current.
After updating, restart your computer and reconnect the monitor. This step alone resolves most connection issues.
6. Still Not Working?
If you’ve tried everything above and the display won’t show, the issue might be with:
- A faulty adapter (especially USB-C > HDMI or docking stations)
- A damaged port or graphics card
At this point, take note of what you’ve tested (ports, cables, devices, and drivers) and reach out to your IT team, or contact Canopy IT Solutions! Having that info ready helps us diagnose and fix your problem faster.