The screen flickers or shows lines
Why is my laptop screen flickering and showing strange lines?
Written by The CommonFixes team · fact checked by CommonFixes review desk
Last updated
Short answer
Either the picture being sent is unstable, which is a driver or refresh rate problem, or the cable carrying it is loose, which is a hardware problem. The quickest thing to try first: find out if the flicker is in the computer or the screen — On Windows, open Task Manager with Control, Shift and Escape. If Task Manager flickers along with everything else, suspect a driver. If it stays steady while the rest flickers, an app is to blame. Most people are done in about 15 minutes.
Full walkthrough below: 4 steps for Windows and Mac, rated easy.
Sounds like this
- •Flashing picture
- •Coloured vertical lines
- •Flicker changes when you move the lid
Why it happens
Either the picture being sent is unstable, which is a driver or refresh rate problem, or the cable carrying it is loose, which is a hardware problem.
Work through these in order
0% done- 1
Find out if the flicker is in the computer or the screen
On Windows, open Task Manager with Control, Shift and Escape. If Task Manager flickers along with everything else, suspect a driver. If it stays steady while the rest flickers, an app is to blame.
- 2
Match the refresh rate to the screen
Open Settings, System, Display, Advanced display, and choose the highest refresh rate offered. A wrong setting after connecting an external monitor causes steady flicker.
- 3
Reinstall the display driver cleanly
In Device Manager, expand Display adapters, right click the card, choose Uninstall device, tick the box to delete the driver, then restart. Windows installs a fresh copy on its own.
- 4
Test the hinge
Slowly tilt the lid back and forth. Lines that appear at certain angles mean the display cable is worn. That is a physical repair, not a settings problem.
If none of that worked
Lines that also show on the manufacturer logo before Windows loads mean the panel itself is failing and needs replacing.
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Who wrote this and how we checked it
The CommonFixes team
Writer and researcher
We are a small group of people who spend our days repairing laptops and desktops for family, friends and small offices. Every guide here starts with a problem someone actually brought to us, and we only write down the steps that put the machine right.
- Everyday repairs
- Windows and Mac
- Plain language
CommonFixes review desk
Technical editor
Before a guide goes live, a second person walks through it on a real machine and checks each instruction against the maker's own support pages. Anything we cannot confirm is removed rather than guessed at.
- Fact checking
- Safety warnings
- Source links
This guide was last updated on 10 August 2026. If a step no longer matches what you see on screen, tell us on the contact page and we will test it again.
A gentle reminder: back up anything you cannot afford to lose before major repairs. If a step ever feels risky, stop and ask a technician. There is no shame in that.