I understand you are trying to get 4k screen resolution on your HP EliteBook 840 G3 notebook.
Let me apologize for any inconvenience this issue may be causing to you.
Would you please attach the Intel Graphics Driver Report? This link will show you how to generate it https://www.intel.com/content/www/us/en/support/graphics-drivers/000005848.html
Are you using a Displayport* to HDMI adapter?
To attach a file, you must click “Use Advanced Editor” on the upper right hand corner of the response box, then the “attach” option will appear on the bottom right hand corner of the response box.
I attached reports from intel utility.
Also I used advice from Samsung support to enable UHD on my TV via : >> Settings -Picture- Expert Settings -HDMI UHD...
However i still get only full HD resolution > 1920 x 1080
Also I tried to install latest intel driver for win7,`( 15.45) from this link
Downloads for Intel® HD Graphics 520 , however I got error message that driver being installed is not valadet for this computer.
When I tried to install driver manualy via zip file... I got another message that I got latest driver.
FYI: my driver version is 20.19.15
From HP support I got info that maybee issue if wrong cable ( not certfied for 4k)
So I am considering to buy new certified cable.
So please check reports and let me know how to fix my issue with 4k on my TV.
Thanks for the information you sent to me.
I would like you to try installing latest graphics driver on a different way. Please download the graphics driver that is on this link https://downloadmirror.intel.com/27058/eng/win64_154605.4771.zip
As soon as the graphics driver has been downloaded on the keyboard press WinLogo key + r, then type in devmgmt.msc, double click on Display Adapters -> Intel HD Graphics -> Driver tab -> Uninstall -> Select the check box Delete the driver software for this device -> OK, restart the computer, and then reinstall the graphics driver with the steps that are on this YouTube video https://www.youtube.com/watch?v=S1KzoQDjMMY
If issue persists please try using the TV in Single Display and let me know if you are able or not to reach 4K screen resolution.
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If issue persists please try with different HDMI cable.
I was wondering if you still need assistance regarding the 4K screen resolution you are trying to get on your HP EliteBook 840 G3 notebook. In case you still need assistance just let me know.