large rectangular boxes periodically flashing on bottom of screen

[Neisenberg001]

So i went to the store today and came home to find some weird boxes flashing on the bottom of my external monitor. they appear to be large rectangular boxes about 1-2in tall by 5in wide, stretching across the bottom edge of the screen. i have tried factory resetting the monitor, updating divers, etc but cant seem to find anything ACTUALLY wrong. does anyone have any ideas??

Monitor is an HP 27f plugged into laptop via HDMI cable

edit: the boxes appear to be screen side, as no matter what program is launched, they appear....

[Hawks_Eye]

Hi @Neisenberg001 

Welcome to the HP Support Community! We're here to help you get back up and running.

Thanks for the clear breakdown — this issue sounds like a display artifact that's likely hardware- or cable-related, not software. Since you’ve already tried a factory reset, driver updates, and confirmed it's not app-specific, here’s a streamlined diagnosis + fix path for your HP 27f monitor flashing box issue:

1. Test with a Different HDMI Cable

Bad HDMI cables can cause exactly this kind of artifact.

Swap to a different HDMI cable (short and good quality if possible).

Also try plugging into a different HDMI port on your laptop if available.

💡 If the problem goes away = cable fault.

2. Try a Different Device on the Monitor

Connect a different laptop or console to the HP 27f via HDMI.

If the boxes still flash → monitor is likely the issue.

If not → your laptop or port may be misbehaving.

3. Lower the Refresh Rate

Go to Display Settings > Advanced Display Settings > Refresh Rate.

Set it to 60Hz even if it’s already default.

Try lowering the resolution slightly too.

Some monitors misbehave at high refresh rates with HDMI, especially if the signal is weak or cable is poor.

4. Check Monitor's OSD (On-Screen Display)

Open the monitor’s built-in menu (via buttons).

Check if the flashing boxes show on top of the OSD or behind it.

If behind: issue is likely from the video signal.

If on top: monitor panel/display logic might be failing.

5. Try DisplayPort (if available)

If your laptop or monitor supports DisplayPort or USB-C video, test with that instead.

If DisplayPort works fine → HDMI port or cable is suspect.

Let me know what you try and what changes — I can narrow it down further if needed.

If my response helped, please mark it as an Accepted Solution! ✅ It helps others and spreads support. 💙 Also, tapping "Yes" on "Was this reply helpful?" makes a big difference! Thanks! 😊

Take care, and have an amazing day!

Regards, 

Hawks_Eye