What causes lines on your monitor screen

Lines on your monitor come from one of three sources: a loose cable connection between your monitor and computer, interference from nearby electronics, or a failing display panel inside the monitor itself. The type of line — horizontal, vertical, flickering, or solid — tells you which one is the problem. Most of the time, lines mean a cable has come loose or bent, which you can fix in under a minute.

When a cable connection weakens, the signal carrying the image breaks up. Your monitor still receives power so it stays on, but the picture develops gaps. Interference from a phone, microwave, or wireless router can create similar patterns. A damaged panel inside the monitor produces lines that do not change when you move cables or restart, which means the monitor itself needs replacement.

Key Takeaways

  • Horizontal or vertical lines that flicker usually mean a loose or bent cable between your monitor and computer — check both ends of the cable first.
  • Lines that stay in the same place and do not change when you restart are a sign of a failing monitor panel, which cannot be repaired.
  • Wireless devices, microwaves, and phone chargers near your monitor can cause temporary line patterns that disappear when you move them away.
  • Restart your computer before trying anything else, because a software glitch can sometimes produce line artifacts that clear on reboot.

Check your cable connections first

The cable that runs from your monitor to your computer is the most common culprit. This cable carries the video signal, and even a small gap at either end breaks the picture. Unplug the cable from both the monitor and the computer, wait five seconds, and plug it back in firmly. You should hear or feel a small click when the connection seats properly. Do this for both ends — the monitor end and the computer end.

While the cable is unplugged, look at the connector pins or contacts. If you see bent pins, corrosion, or visible damage, the cable itself is failing and needs replacement. Also check the cable along its entire length for kinks, pinches, or places where it has been bent sharply. A kinked cable can work intermittently, producing lines that come and go. If you find damage, order a replacement cable that matches your monitor's connection type — HDMI, DisplayPort, USB-C, or VGA, depending on your setup.

Restart your computer and monitor

Before you assume the hardware is broken, restart both devices. Power off your computer completely, then unplug your monitor from the wall outlet and wait ten seconds. Plug the monitor back in and turn on your computer. This clears temporary glitches in the graphics card or monitor firmware that can produce line artifacts on screen.

If the lines disappear after the restart, the problem was a software hiccup and you are done. If the lines return when ready, move to the next step. Do not skip this step even if it seems too straightforward — a surprising number of display problems clear on reboot.

Move wireless devices and electronics away from your monitor

Wireless devices and high-power electronics can interfere with your monitor's signal, especially if you use an older monitor or a long cable. Move your phone, wireless mouse receiver, microwave, or cordless phone away from your monitor and cables. If the lines disappear or change, you have found the source. Keep these devices at least two feet away from your monitor and its cables going forward.

This is most common in small spaces like dorm rooms or tight desks where a phone charger, router, or microwave sits inches from your monitor. Rearranging your desk to separate these devices often solves the problem permanently. If you cannot move the devices, moving your monitor cable to a different path — away from the interference source — sometimes helps.

Update or reinstall your graphics driver

Your graphics driver is the software that tells your computer how to send a picture to your monitor. An outdated or corrupted driver can produce lines, especially if the lines appeared after a Windows or Mac update. Visit the website of your graphics card manufacturer — NVIDIA, AMD, or Intel — and read the latest driver for your specific card and operating system. Install it, restart your computer, and check whether the lines are gone.

If you cannot find your graphics card model, right-click your desktop and look for an option like "NVIDIA Control Panel" or "AMD Radeon Settings". These tell you which card you have. On a Mac, go to the Apple menu, choose About This Mac, and look under Graphics. Once you have the driver installed, the lines should clear within a few minutes of restart.

Determine whether the monitor itself is failing

If the lines stay in exactly the same place on your screen, do not change when you restart, and do not disappear when you move cables or wireless devices, the monitor panel itself is failing. This is a hardware failure inside the monitor that cannot be fixed by adjusting cables or software. The monitor will need to be replaced.

You can confirm this by connecting your monitor to a different computer if you have one available. If the same lines appear in the same spots on the second computer, the monitor is definitely the problem. If the lines disappear on the second computer, the issue is with your original computer's graphics card or driver, not the monitor.

When to replace your cable versus your monitor

A replacement cable costs between ten and thirty dollars and takes two minutes to install. A replacement monitor costs between one hundred and five hundred dollars depending on size and features. Always try the cable first. If you have had the monitor for more than five years and the panel is failing, replacement is usually cheaper than repair — most monitors cannot be repaired economically.

If your monitor is under warranty, check the paperwork or the manufacturer's website. Many monitors come with a one- to three-year warranty that covers panel failure. Contact the manufacturer with your serial number and proof of purchase, and they may replace it at no cost. If the monitor is out of warranty and the panel is failing, buying a new one is your only option.

Frequently Asked Questions

Can I fix a monitor with lines myself?

You can fix lines caused by loose cables, interference, or driver problems yourself in minutes. Lines caused by a failing monitor panel cannot be fixed — the monitor must be replaced. If you are not comfortable opening your monitor or working with electronics, do not attempt internal repairs.

Why do the lines only appear sometimes?

Intermittent lines usually mean a cable connection is loose or partially bent. The cable works sometimes and fails other times depending on how the monitor is jostled or how the cable flexes. Reseating the cable firmly at both ends usually solves this. If lines come and go randomly, a failing cable is the most likely cause.

Do I need to buy the exact same cable my monitor came with?

No. You need a cable that matches your monitor's connection type — HDMI, DisplayPort, USB-C, or VGA. Any brand-name cable of the correct type will work. Avoid extremely cheap cables, as they may have poor shielding and cause interference problems.

What if I see lines only in certain programs or games?

Lines that appear only in specific programs usually point to a graphics driver problem or a setting within that program. Update your graphics driver first. If the lines persist, check the program's display settings for resolution or refresh rate options that might be causing the issue.

Is it safe to use a monitor with lines on the screen?

A monitor with lines is safe to use. It will not damage your computer or cause injury. However, if the lines are caused by a failing panel, they will usually get worse over time until the monitor becomes unusable. If the cause is a loose cable, using the monitor with a loose connection will not harm anything, but you should reseat the cable to restore the proper picture.