# Why are there horizontal or vertical lines appearing on my PC screen? There are several possible causes behind the appearance of [PC screen lines](https://devicefixes.com/blog/pc-screen-lines/): outdated graphics drivers, loose display cables, damage to the monitor or graphics card issues. The lines can be straight up and down, side by side, or wavy. Placing another monitor on the computer may help you identify if the problem is with the monitor or with the hardware of the PC. The first troubleshooting steps are to check the cable connections and update the drivers.