Lines on Monitor: Every Type, Cause and Fix
Table of contents
Lines on a monitor are almost always caused by one of three things: the video cable or port, the graphics card and its driver, or the panel inside the monitor. The fastest way to tell them apart is to open the monitor’s own on-screen menu. If the lines run across the menu as well, the fault is inside the monitor. If the menu is clean and the lines only show over your desktop, start with the cable and the driver, which are cheap and quick to fix.
This guide covers every common type of line, what each one points to, and the first thing to try. Where a type has its own detailed guide, the table below links to it.
The 60-second triage: monitor, cable or PC?
Two quick tests sort nearly every case before you change a single setting.
Test 1: the menu test. Press the monitor’s menu button so the on-screen display (OSD) opens. You can also unplug the video cable and look at the “No Signal” box. The monitor draws these images itself, with no help from your PC. So if the lines cross the menu or the No Signal box, the problem is inside the monitor. LG’s support guide for lines on the screen uses the same check and says a monitor that still shows lines with the cable removed needs a technician.
Test 2: the screenshot test. Press the Windows key + Print Screen, then open the saved image on another device, such as your phone. A screenshot copies what the graphics card drew. If the lines are in the image, the graphics card, its driver or an app created them. If the image is clean, the lines were added after that point, in the cable, the monitor or, now and then, the graphics card’s output port. The same test sorts out screen artifacts such as sparkles and blocks.
If both tests are clean, connect a second screen or a TV. Lines that follow the PC to the other screen mean the graphics card. Lines that stay on the first monitor with a new cable and a new PC point to the monitor. Some monitors also have a built-in test that draws a pattern with no PC attached. Samsung Smart Monitors have a Self Diagnosis Picture Test, and many Dell monitors have a built-in diagnostic in the menu. Lines in either test mean the monitor is at fault.
Every type of line, and what it means
Use this table to match what you see to the likely cause and the first fix. The last column links to the full guide where one exists.
| Line type | Likely cause | First fix | Full guide |
|---|---|---|---|
| Vertical lines, one or many | Cable, GPU driver, or panel column driver | Menu test, then swap the cable | Vertical lines guide |
| Horizontal lines | Cable, refresh rate, interference, or panel row driver | Lower the refresh rate, swap the cable | See the section below |
| Single thin colored line (red, green, blue) | Failed column driver or bond on the panel | Menu test; usually a warranty case | Vertical lines guide |
| Faint white or gray line | Weak panel bond, pressure damage, or a stuck column | Check for pressure on the frame | Faint white line guide |
| Flickering or moving lines | Loose cable, bandwidth limit, or overclocked refresh | Reseat the cable, set a standard refresh rate | See the section below |
| Lines on one input only | Faulty port, cable, or that input's settings | Try another cable on the same port | See the section below |
| Shimmering lines on certain patterns | Pixel inversion, normal panel behavior | Adjust overdrive or refresh rate | Pixel inversion guide |
| Lines on a laptop screen | Hinge ribbon cable, GPU, or panel | Tilt the lid slowly and watch | Laptop lines guide |
Vertical lines
Vertical lines are the most common type. They can come from almost anywhere in the chain, from a bad cable to a failing graphics card to a cracked bond along the top edge of the panel, where the column driver chips sit. Lines that are sharp, one pixel wide and stay in a fixed spot usually mean that bond has failed. Our vertical lines on monitor guide walks through seven fixes in order and explains when it becomes a warranty or repair case.
Single colored line
A single red, green, blue or purple line running top to bottom is almost always hardware. Each column of pixels gets its signal from a tiny chip bonded to the glass. When that link breaks, one column shows a fixed color or stays dark. Run the menu test. If the line crosses the menu, no cable or driver will fix it.
Faint white line
A thin, pale line that is easy to miss on dark content but obvious on white is a separate case. It often follows pressure on the frame, a knock, or a monitor that was carried by the screen. Our guide to the faint white line on a monitor covers how to tell a weak bond from a stuck column, and what you can safely try.
Horizontal lines on a monitor
Horizontal lines usually point to the signal, not the panel, so start with the cable and the refresh rate. They often look like thin stripes, a band of noise that rolls up or down, or a section of the picture that seems to tear sideways.
These are the main causes, from most to least likely:
- Cable or connection. A loose, kinked or cheap cable can drop data and leave thin horizontal streaks or sparkles. Reseat both ends, then try a known-good cable without adapters.
- Refresh rate set too high. If you raised the refresh rate in the monitor’s menu or used a custom resolution tool, the signal may be past what the panel or cable can handle. Go back to the refresh rate Windows marks as standard for your monitor.
- Interference on analog VGA. On older VGA connections, a nearby speaker, phone charger or power brick can cause wavy or rolling lines. Move other devices away, or switch to HDMI or DisplayPort.
- Panel row driver fault. A sharp horizontal line across the full width, in a fixed spot, comes from the side edge of the panel where the row driver circuits sit. Like a column fault, it shows in the menu test and needs a repair or replacement.
A quick check helps here. Lower the refresh rate from 144 Hz to 60 Hz in Settings, then System, Display and Advanced display. If the lines vanish at 60 Hz and return at 144 Hz, the cable or port cannot carry the full signal. A certified cable usually fixes it.
Flickering lines and lines on one input only
Flickering lines that come and go are a signal problem in most cases. The picture is getting through, but some data is lost along the way. Reseat the cable, swap it, and try a standard refresh rate. If you use variable refresh (G-SYNC or FreeSync), switch it off briefly to see if the lines stop. Lines that only appear in fast games can also be overdrive artifacts, which our guide to what overdrive does on a monitor explains.
If lines appear on one input but not another, for example on HDMI 1 but not DisplayPort, the screen itself is fine. The fault is in that port, that cable, or settings tied to that input, such as a different refresh rate or color format. Try a fresh cable on the same port first. If the lines stay, the port on the monitor or the graphics card may be damaged. Our guide on how to connect a monitor covers which connection to use for higher refresh rates.
Laptop screens vs desktop monitors
On a desktop monitor, the video cable is outside and easy to swap. On a laptop, the signal runs through a thin ribbon cable that passes through the hinge, and that is where many laptop lines start. Open and close the lid slowly. If the lines change, flicker or vanish at certain angles, the hinge cable is the likely cause. Plug the laptop into an external monitor as well. Lines on the laptop panel only mean the panel or its cable. Lines on both screens mean the graphics chip or driver. Our guide to laptop screen vertical lines goes through each step.
When lines mean repair or replacement
Once the menu test shows lines inside the monitor, check the warranty first. Many brands treat column and row line faults as a panel defect, while cracked glass or pressure damage is usually excluded. Do not open the monitor yourself while it is still covered.
Out of warranty, a new panel often costs close to a new monitor, so repair only makes sense on expensive or large displays. Our ViewSonic monitor repair guide breaks down typical repair costs. If you see other faults besides lines, such as flicker, blur or dead pixels, our monitor screen issues guide covers those.
Conclusion
Lines on a monitor come from the cable, the graphics card or the panel, and two tests tell you which. Lines in the monitor’s own menu mean the monitor is at fault. Lines in a screenshot mean the GPU or software. Anything else points to the cable or port, so reseat it, swap it and drop to a standard refresh rate. A good result is a clean picture on every input. For more fixes, see the troubleshooting hub or the full SubInsider monitor knowledge base.
Frequently asked questions
Can lines on a monitor go away on their own?
Sometimes. Lines caused by a loose cable, a driver glitch or a bad refresh setting can vanish after a restart or a reseat. Lines that stay put in the same spot, and show in the monitor's own menu, come from the panel and almost never clear on their own. They usually spread over time.
Are lines on a monitor a hardware or software problem?
Take a screenshot. If the lines appear in the saved image, the graphics card or software drew them. If the screenshot is clean, the lines are added later, usually in the cable or the monitor. Lines in the monitor's menu or No Signal screen are always hardware inside the monitor.
Can a bad HDMI cable cause lines on the screen?
Yes. A damaged, loose or underpowered HDMI cable can cause flickering lines, sparkles, colored stripes or a picture that cuts in and out. The lines often move or change when you touch the cable. Swap in a certified cable rated for your resolution and refresh rate to rule it out.
Is it worth fixing lines on a monitor?
If a cable, port or driver is the cause, the fix is cheap or free. If the panel or its internal driver circuits failed, a repair usually costs close to the price of a new monitor, so it is only worth it under warranty or on an expensive high-end display.
Why do lines appear when I press on my monitor?
Pressing the screen flexes the panel and disturbs a weak connection between the glass and its driver circuits along the edge. That points to a failing bond or ribbon inside the monitor, not a setting. Stop pressing on it, since repeated flexing can turn a temporary line into a permanent one.