Screen flickering, flashing or showing lines

One quick test separates the two main causes: open Task Manager and watch whether it flickers too.

What you seeThe screen blinks, dims and brightens, or shows horizontal lines

The Task Manager test

Press Ctrl + Shift + Esc to open Task Manager and watch its window.

• Task Manager flickers along with everything else: the cause is the display driver or the hardware. Go to part A.
• Task Manager stays steady while the rest flickers: the cause is an app. Go to part B.

A. Display driver or settings

1. Restart the graphics driver: press Windows key + Ctrl + Shift + B.
2. Check the refresh rate. Settings › System › Display › Advanced display › Choose a refresh rate. Pick the highest the list offers, or 60 Hz as a test. On some laptops, "Dynamic" refresh rate causes flicker; choose a fixed rate.
3. Update the graphics driver. Settings › Windows Update › Advanced options › Optional updates, or better, the driver for your model from the laptop maker's support page, or from Intel, AMD or NVIDIA for a desktop card.
4. Or roll it back, if the flicker began after an update: right-click Start › Device Manager › Display adapters › your adapter › Properties › Driver › Roll Back Driver.
5. Reinstall the driver cleanly: Device Manager › Display adapters › right-click › Uninstall device, tick "Attempt to remove the driver for this device", restart, then install the maker's driver. The screen may be low-resolution for a minute; that is normal.
6. Turn off adaptive brightness and power savers. Settings › System › Display › Brightness: untick "Change brightness automatically when lighting changes" and "Change brightness based on content". In the Intel or AMD graphics app, turn off "Display Power Savings" or "Vari-Bright".
7. Turn off HDR and variable refresh rate for a test: Settings › System › Display › HDR, and Display › Graphics › Default graphics settings.

B. An app is the cause

1. Think of what was installed just before it began. Known offenders are old antivirus programs, screen-tinting or wallpaper tools, and some cloud or control-panel add-ons.
2. Update that app, or uninstall it: Settings › Apps › Installed apps.
3. Not sure which? Start in Safe Mode. If the flicker stops there, do a clean start: Windows key + R › msconfig › Services › tick "Hide all Microsoft services" › Disable all, and Task Manager › Startup apps › disable all. Restart, then turn items back on a few at a time until the flicker returns.

C. Cable, monitor and hardware checks

• External monitor: reseat the cable at both ends; try another cable and another port (HDMI or DisplayPort). Try the monitor with another device. Cheap or long cables fail at high resolutions and refresh rates.
• Laptop: connect an external monitor or TV. If the external screen is steady while the laptop's own flickers, and the flicker changes when you move the lid, the display cable in the hinge or the panel is failing: a service job.
• Flicker in the BIOS set-up screen too (before Windows loads) means hardware, not Windows.
• Flicker only on battery, or only at low brightness: a power-saving setting (step A6), or the panel dimming by rapid switching. Raise the brightness, or change the setting.
• Lines or blocks of colour, with crashes in games: the graphics chip may be overheating. Clean the vents and fans.

Flicker only in one program or in the browser

Turn off hardware acceleration in that program. In Chrome or Edge: Settings › System › "Use graphics acceleration when available", off, then relaunch. Update the program and the graphics driver.

For Windows 11 and Windows 10. Written in November 2026. Menus move between updates; use the search box in Settings if a name differs. Back up important files before any step that resets, repairs a disk or opens the computer. This is an independent guide, not connected with Microsoft.