Mac Display Flickering? How to Fix Screen Flicker
Mac screen flickering, flashing black, or showing lines? Here's how to diagnose and fix display flickering on MacBook, iMac, and external monitors.
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Types of Display Flickering
- Random black flashes: Screen goes black briefly then returns
- Constant flicker: Display stutters or shakes continuously
- Horizontal/vertical lines: Lines appear across the screen
- Flicker when moving lid: Flexgate-style cable issue (2016-2019 MacBook Pro)
- External monitor flickering: Connected display is unstable
- Only happens on battery: Power-related display issue
Fixes to Try
1 Restart Your Mac
Clears GPU driver glitches that cause flickering:
- Go to Apple menu → Restart
- After restart, observe if flickering continues
2 Check for macOS Updates
Many display flickering bugs are fixed in updates:
- Go to System Settings → General → Software Update
- Install any available updates
- Restart and monitor the display
3 Disable "Automatically Adjust Brightness"
Auto-brightness can cause flickering on some Macs:
- Go to System Settings → Displays
- Turn off "Automatically adjust brightness"
- Set brightness manually to see if flickering stops
4 Disable True Tone
True Tone's color adjustments can sometimes cause visual instability:
- Go to System Settings → Displays
- Uncheck "True Tone"
- Test if flickering improves
5 Reset NVRAM (Intel Macs)
NVRAM stores display settings that can become corrupted:
- Shut down your Mac
- Turn on and immediately hold Option + Command + P + R
- Hold for about 20 seconds
- Release and let Mac boot normally
6 Check GPU Usage
A maxed-out GPU can cause display issues:
- Open Activity Monitor (search in Spotlight)
- Click the GPU History button in the Window menu
- If GPU is pegged at 100%, find the app causing it
- Close or quit that app
7 For External Monitors: Check Cable and Connection
- Try a different cable (HDMI, DisplayPort, or USB-C)
- Connect directly to Mac rather than through a hub
- Try a different port on your Mac
- Adjust the monitor's refresh rate: System Settings → Displays → Refresh Rate
8 Boot in Safe Mode
Tests if third-party software is causing GPU/display issues:
Apple Silicon: Shut down → Hold power → Hold Shift → Continue in Safe Mode
Intel: Restart → Hold Shift until login screen
If flickering stops in Safe Mode, a third-party app or GPU-intensive process is the cause.
9 Flexgate Check (2016-2019 MacBook Pro)
These models have a known display cable issue:
- Symptoms: Backlight fails at low lid angles, "stage lighting" effect at bottom of screen
- Apple extended the repair program for affected models
- Check Apple's service program to see if your serial number qualifies for free repair
Still Flickering?
Persistent flickering that doesn't respond to software fixes is usually a hardware issue — failing display cable, GPU, or backlight. This requires professional diagnosis.
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