Screen flickering on an HP EliteBook 840 is incredibly distracting, making it hard to focus on your work. The display might flash, show horizontal lines, or have intermittent blackouts. Let's get it fixed.
Update Your Display Drivers
Outdated or corrupted graphics drivers are the most common cause of flickering. I'd start here. Open the HP Support Assistant app, which is great for managing enterprise drivers, and check for any recommended updates for your Intel or AMD graphics.
You can also go directly to the HP support website, enter your specific EliteBook 840 model number, and download the latest display driver from there. Installing the manufacturer-provided driver is often more reliable than the generic one from Windows Update.
Adjust the Screen Refresh Rate
Right-click on your desktop and select Display settings. Scroll down and click Advanced display. Here, you can see and change your refresh rate.
Try switching it. If it's set to 60Hz, select 59.94Hz, or vice versa. Sometimes a slight mismatch between the panel and the driver's timing can cause a persistent flicker that this simple switch resolves.
Disconnect from Docking Stations
If the flickering only happens when your EliteBook is connected to a docking station, that's a known culprit. The issue often lies with the USB-C connection or the dock's firmware.
Disconnect the laptop and use it directly on its own screen. If the flickering stops, try updating the docking station's drivers and firmware. Also, test with a different USB-C cable if you have one available.
Boot into Safe Mode
This test tells you if the problem is with Windows or your core hardware. Restart your laptop and press F8 repeatedly as it boots (or hold Shift while clicking Restart in Windows to access advanced startup). Choose Safe Mode.
If the screen is perfectly stable in Safe Mode, a third-party app, service, or driver you've installed is causing the conflict. You'll need to pinpoint it by process of elimination after you boot back normally.
Check Task Manager for App Conflicts
Press Ctrl + Shift + Esc to open Task Manager. Watch the Task Manager window itself closely. If it flickers along with everything else, the issue is likely system-wide, like a driver.
If Task Manager remains perfectly stable while your desktop and other windows flicker, a specific application is to blame. Common offenders include certain antivirus suites, VPN clients, or screen-sharing software.
Run HP PC Hardware Diagnostics
HP builds a great diagnostic tool right into your laptop. Restart the computer and immediately press the F2 key repeatedly. This boots into the HP PC Hardware Diagnostics UEFI environment.
Run the system fast test, and then specifically run the video display test. This will check your screen and graphics hardware for failures. Any errors found here point to a likely hardware problem.
Disable Hardware Acceleration in Apps
Applications like web browsers and video players use your GPU to render content. A conflict here can cause flickering. In Google Chrome, go to Settings > System and turn off Use hardware acceleration when available.
Do the same in other apps like Microsoft Teams or Zoom if you notice the flickering primarily during video calls. This shifts the rendering workload off the GPU and can stop the flicker immediately.
Inspect the Internal Display Cable
This is a hardware check. Does the flickering get worse when you open or close the lid, or gently flex the screen bezel? The internal display cable (an eDP cable) can become loose or damaged over time from hinge movement.
While this isn't a simple fix, identifying it saves time. A loose cable typically requires opening the laptop chassis to reseat it, which is best left to a professional if you're not comfortable with internal repairs.
Reset or Update the BIOS
Corrupted BIOS settings can sometimes affect display stability. Restart your laptop and press F10 to enter the BIOS Setup. Look for an option to "Load Setup Defaults" or "Restore Factory Defaults," save, and exit.
The good news is the EliteBook 840 has HP Sure Start. If the BIOS becomes corrupted, this feature should automatically attempt to recover it on the next boot. For a manual update, download the latest BIOS from HP's support site and install it from within Windows.
