What causes a line on your screen
A line running across or down your computer screen usually comes from one of three sources: a problem with the display cable connecting your monitor to the computer, damage to the monitor itself, or a graphics driver issue in your operating system. The line may be thin or thick, solid or flickering, and it might appear in one spot or move around as you use your computer.
The most common cause is a loose or damaged cable. If your monitor connects to your computer with a cable (HDMI, DisplayPort, VGA, or USB-C), that cable can work loose from vibration or accidental bumping, or it can develop an internal break that disrupts the signal. A second common cause is physical damage to the monitor screen itself—a crack, pressure damage, or internal component failure. The third possibility is a software issue: outdated or corrupted graphics drivers can send incorrect signals to your monitor, creating lines that appear and disappear unpredictably.
Key Takeaways
- A line on your screen usually means either the cable connecting your monitor is loose or damaged, the monitor itself has a hardware problem, or your graphics driver needs updating.
- Start by checking that all cables are firmly seated in their ports on both the monitor and the computer, then try a different cable if you have one available.
- If the line appears only in certain programs or when you move your mouse, the problem is likely software-related and a driver update may fix it.
- If the line stays in the exact same spot no matter what you do on your computer, the monitor itself is probably damaged and may need replacement.
Check your cable connection first
Before assuming your monitor or computer is broken, verify that the cable is fully connected. Power off your monitor and computer, then locate the cable running from the back of your monitor to the port on your computer (or to a docking station if you use a laptop). Gently pull the cable out completely, inspect both ends for bent pins or visible damage, and push it back in firmly until you hear or feel a click. If your cable has a locking mechanism (small screws on either end), tighten those as well.
If you have access to a second monitor cable of the same type, connect that cable instead and power on your computer. If the line disappears with the new cable, your original cable is damaged and needs replacement. If the line persists with a different cable, the problem lies elsewhere. Leave the new cable connected if it works, or reconnect the original one if both cables produce the same result.
Restart your computer and check for driver updates
A graphics driver is the software that tells your computer how to communicate with your monitor. If that driver becomes corrupted or outdated, it can cause lines, flickering, or color problems. Restart your computer first—this clears temporary memory and often resolves software glitches. After restart, check whether the line is still there and whether it behaves the same way.
If the line remains, update your graphics driver. On Windows, right-click the Start menu, select Device Manager, expand Display adapters, right-click your graphics card (usually Intel, NVIDIA, or AMD), and select Update driver. Choose Search automatically for updated driver software. On Mac, go to System Settings, select General, then Software Update, and install any available updates. Restart your computer after the update completes. If a driver update was available and you installed it, the line should disappear.
Determine whether the problem is hardware or software
Pay attention to when and where the line appears. If the line stays in exactly the same position on your screen no matter what program you open or what you do with your mouse, the monitor itself likely has a hardware problem. If the line moves, changes, flickers, or appears only when you use certain programs, the issue is probably software-related.
Another test: restart your computer and enter the BIOS or UEFI settings before Windows or macOS loads. On most computers, you press Delete, F2, or F12 during startup (the key appears on your boot screen). If the line is visible in BIOS, the monitor or cable is the problem. If the line is not visible in BIOS but appears after your operating system loads, a driver or software issue is responsible. Exit BIOS without making changes by pressing Escape or selecting Exit Without Saving.
What to do if the monitor itself is damaged
If you have confirmed the cable is find, tried a different cable, updated your drivers, and the line remains in the same spot, your monitor has internal damage. This could be a cracked LCD panel, a failed internal component, or a problem with the monitor's power supply. Unfortunately, monitor repairs are rarely worth the cost—replacement is usually the better option.
Before you buy a new monitor, check whether your computer is still under warranty. If you purchased the monitor within the last year or two, the manufacturer may replace it at no cost. Look for the receipt or warranty card, or visit the manufacturer's website and enter your monitor's serial number (usually on a sticker on the back). If the monitor is out of warranty, budget for a replacement that matches your needs in size and resolution.
Troubleshooting for laptop screens
If you are using a laptop and see a line on the built-in screen, the cable connecting the screen to the motherboard may be loose or damaged. This is more difficult to fix than a monitor cable because it requires opening the laptop. If your laptop is under warranty, contact the manufacturer or an authorized repair center rather than opening it yourself.
If your laptop is out of warranty and you are comfortable opening it, search online for your specific laptop model plus "screen cable replacement" to find a guide. The process varies widely by manufacturer. Alternatively, you can connect an external monitor to your laptop using HDMI or USB-C. If the external monitor displays without a line, your laptop screen is the problem. If the line appears on the external monitor too, the graphics card or driver is responsible.
When to replace your monitor versus repair it
Monitor repair shops exist but are uncommon, and the cost of repair often approaches the cost of a new monitor. A basic 24-inch monitor costs between $100 and $200 new. Unless your monitor is a high-end model worth $500 or more, replacement is almost always more practical than repair. Check your monitor's model number (on the back or bottom) and search online for the current price before deciding.
If you decide to replace your monitor, note the size (measured diagonally across the screen), the resolution (1920×1080, 2560×1440, and so on), and the type of ports you need (HDMI, DisplayPort, USB-C). Bring this information to a computer retailer or use it to search online. Most modern monitors work with any computer, so you have many options at different price points.
Frequently Asked Questions
Can a line on my screen go away on its own?
A line caused by a loose cable may disappear if the cable shifts back into place, but this is unreliable. A line caused by a software issue may disappear after a driver update or restart. A line caused by physical damage to the monitor will not go away without repair or replacement.
Is a line on my screen dangerous?
A line on your screen is not dangerous to you or your data. It will not spread or cause other problems. However, it may indicate that a cable is about to fail completely, so addressing it sooner rather than later prevents a complete loss of display.
What if the line appears only when I move my mouse?
This usually indicates a software issue, often related to graphics drivers or display settings. Update your graphics driver and restart your computer. If the problem persists, try lowering your screen refresh rate in display settings: right-click your desktop on Windows, select Display settings, scroll to Advanced display, and look for Refresh rate.
Can dust or dirt cause a line on my screen?
Dust on the outside of your monitor will not cause a line. Dust inside the monitor is possible but rare, and cleaning the inside requires opening the monitor, which is not recommended unless you have experience with electronics. If dust is the problem, replacement is safer than attempting to clean it.
Do I need to replace my computer if my monitor has a line?
No. Your computer is fine. The monitor is a separate device that can be replaced independently. Disconnect the monitor, connect a different one (borrow one from a friend if needed), and verify that the new monitor works without a line. Then you know the monitor is the problem, not your computer.