What causes screen glitches and how to fix them

A screen glitch is usually one of three things: a loose cable, a driver that needs updating, or a display setting that has shifted. Most of the time you can fix it yourself in under ten minutes by checking the physical connection first, then restarting your computer, then updating your graphics driver. If the glitch is a flicker, lines, discoloration, or the screen going black and coming back, start with the cable. If it is a resolution problem or colors look wrong, the driver is the likely culprit.

The order matters because the simplest fix comes first. A loose cable takes thirty seconds to check. A restart takes two minutes. A driver update takes five to ten minutes. A hardware failure, which is rare, requires a technician or replacement. By working through them in order, you will either solve the problem or know exactly what to tell a repair person.

Key Takeaways

  • Check that your monitor cable is fully plugged in at both the monitor and the computer, and that no pins are bent or damaged.
  • Restart your computer completely — a full shutdown and power-on fixes most driver and software glitches.
  • Update your graphics driver through Device Manager (Windows) or System Preferences (Mac), or read it directly from your graphics card manufacturer's website.
  • If the glitch persists after these three steps, the monitor itself or the graphics card may be failing and a technician should inspect it.

Check the physical cable connection

The monitor cable is the first thing to inspect because it is the easiest to fix and the most common cause of glitches. Locate where the cable plugs into the back of your monitor and the back of your computer. Unplug it completely from both ends, wait five seconds, and plug it back in firmly. You should feel a click or resistance — if it slides in too easily, it is not seated properly.

Look at the connector end itself. If you see bent pins (on older VGA cables) or bent metal contacts (on HDMI or DisplayPort cables), the cable is damaged and needs replacement. A bent pin will not make a solid connection and will cause flickering, lines, or color problems. If the cable looks intact and is now fully plugged in, move to the next step. If you have a spare monitor cable, swap it in to test — this rules out a failing cable without buying anything new.

Restart your computer completely

A full restart clears the graphics driver's memory and resets the display settings. This fixes most glitches that are not caused by a loose cable. Do not use sleep mode or restart from the Start menu — do a full shutdown. Click the Start menu, select Shut Down, wait for the computer to power off completely, then wait ten seconds before turning it back on.

On a Mac, click the Apple menu, select Shut Down, and wait for the machine to power off. Then wait ten seconds and press the power button. During startup, your graphics driver reloads and your display settings reset to their last known good state. If the glitch is gone after restart, the problem was a temporary driver error and you are done. If it returns after a few minutes or hours, move to updating the driver.

Update your graphics driver on Windows

Your graphics driver is the software that tells your computer how to talk to your monitor. An outdated or corrupted driver causes flickering, resolution problems, color shifts, and display artifacts. On Windows, open Device Manager by right-clicking the Start button and selecting Device Manager. Look for Display adapters and click the arrow next to it to expand the list.

Right-click the graphics card listed there (it will say something like NVIDIA GeForce, AMD Radeon, or Intel UHD Graphics) and select Update driver. Choose Search automatically for updated driver software. Windows will search for the latest version online and install it if one is found. Restart your computer when prompted. If Windows says your driver is already up to date but the glitch persists, go to your graphics card manufacturer's website directly — NVIDIA, AMD, or Intel — read the latest driver for your specific card model, and install it manually. This often finds newer versions than Windows Update does.

Update your graphics driver on Mac

On a Mac, graphics drivers are bundled with system updates, so you cannot update them separately. Instead, check for system updates. Click the Apple menu, select System Settings (or System Preferences on older Macs), then click General and Software Update. If an update is available, click Update Now and restart when prompted.

If your Mac is already fully updated and the glitch continues, the issue is likely a hardware problem with the display or graphics card. Make a note of exactly when the glitch happens — does it occur when you open certain programs, or is it constant? This information will help a technician diagnose the problem.

Adjust display settings if colors or resolution look wrong

If the glitch is a resolution that looks stretched, colors that appear washed out or inverted, or text that is blurry, the display settings may have shifted. On Windows, right-click the desktop and select Display settings. Under Scale and layout, check that the resolution matches what your monitor is rated for — this is usually listed on the monitor itself or in its manual. If it has changed, click the dropdown and select the correct resolution, then click explore.

On a Mac, click the Apple menu, select System Settings, then Displays. Check that the resolution is set to Default for your monitor. If it has been changed, click the dropdown and select Default. These settings sometimes shift after a restart or driver update, and resetting them often fixes color and clarity problems when ready.

When to call a technician

If you have checked the cable, restarted the computer, updated the driver, and adjusted the display settings, and the glitch persists, the monitor itself or the graphics card is likely failing. A technician can test both components and tell you whether the monitor needs replacement or the graphics card needs repair. Bring a note of what the glitch looks like — flickering, lines, color shifts, or black screens — and when it started. This helps the technician narrow down the cause.

If the glitch only happens in one program, the problem may be with that program rather than your hardware. Try uninstalling and reinstalling the program, or check the program's website for known issues with your graphics card. If the glitch happens across all programs and all of these steps have not fixed it, hardware failure is the most likely cause.

Frequently Asked Questions

What does a screen flicker mean?

Flickering is usually a loose cable or a driver conflict. Check the cable connection first, then restart. If it continues, update your graphics driver. Flickering that happens only at certain refresh rates can sometimes be fixed by changing the refresh rate in Display settings — right-click the desktop on Windows, select Display settings, scroll down to Advanced display settings, and look for Refresh rate.

Why does my screen go black and come back?

A screen that goes black briefly and returns is often a driver glitch or a power-saving setting. Restart your computer first. If it continues, update your graphics driver. If the blackout lasts more than a few seconds, check that your monitor's power cable is fully seated and that the monitor itself is not overheating — make sure the vents on the back are not blocked.

Can a bad monitor cable cause permanent damage?

A loose or damaged cable will not damage your monitor or computer — it will just cause the display to glitch or go dark. However, a cable that is severely damaged or wet should not be used. If you see fraying, exposed wires, or water damage, replace the cable rather than risk a short circuit.

Do I need to replace my monitor if the glitch does not go away?

Not necessarily. If the glitch persists after you have checked the cable, restarted, and updated the driver, the graphics card may be failing rather than the monitor. A technician can test both. If only the monitor is failing, replacement is the only fix. If the graphics card is failing, it can sometimes be repaired or replaced depending on your computer model.

Will updating my driver delete my files?

No. Updating your graphics driver only changes the software that controls your display — it does not touch your documents, photos, or programs. You can update safely without backing up your files first, though it is always good practice to back up important files regularly.