Question Can't change resolution of4K TV set up as second monitor

Solo Popo

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I used to have a 1080p TV set up as a second monitor with hdmi. I recently bought a new 4k tv (sony x85j), but when I connect it to my gpu with hdmi the option to change resolution is greyed out in windows and it defaults to 720p. All I did was unplug the hdmi cable that was in the old tv and put it in the new one. Applications I launch within windows can be set to 4k and it works fine. But for some reason I can't change the resolution in windows itself. I tried plugging it in to a different input on the TV but didn't have any luck with that. I haven't tried changing the GPU (rtx 3070) input yet though. I have a new HDMI cable coming in the mail that I hope will resolve the issue, but I'm beginning to think that may not work because the TV seems to handle 4K resolution fine if it's a windows app. I am considering uninstalling and reinstalling my GPU driver, but I have put this off for now until I test the new HDMI cable. I've had weird issues with my second monitor before and only want to mess with the drivers as a last resort. Any recommendations are greatly appreciated.
 
where are you attempting to set the resolution in Windows?
if you haven't; check in Settings > System > Display > Advanced display settings > Display adapter properties.
here you may be able to alter the refresh rate to allow 2160p.
there are older HDMI iterations that cannot handle the bandwidth to output 2160p at over 30Hz, or at all.
so lowering the refresh rate may allow higher resolution.

there's also a chance that you need to setup the TV's input options through it's own settings before Windows can detect it's proper resolution.
 
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Solo Popo

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I was trying to change it in settings > system > display. In advanced display settings I can see the tv is set to 30 hz by default but it allows me to set it up to 60 hz. What's strange is it reports my resolution as being 4K. And come to think of it, the screen does look pretty sharp. But the windows UI is scaled up as if the resolution is low and icons on the screen are huge. I have the option to change refresh rates in display adapter properties, but not resolution. Windows recognizes the display as SONY TV *30. If I were to guess I'd say the 30 represents the refresh rate. As far as input settings go, there is standard format, enhanced format, dolby vision, and vrr. The hdmi input the computer is plugged into only has standard and enhanced format. I've tried both settings. Further than that I can customize a source to be either a cable box, player, recorder, game, audio system or "other". I've tried game and other.
 
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the windows UI is scaled up as if the resolution is low and icons on the screen are huge
Windows will usually auto-adjust the scaling for higher resolution to ridiculous sizes.
the default for my ultra-wide 1440p makes icons so large they overlap on the screen.

my 2160p TV had text so large you could see the pixels in the letters and only ~10 words would fit per line.
In advanced display settings I can see the tv is set to 30 hz by default but it allows me to set it up to 60 hz. What's strange is it reports my resolution as being 4K. And come to think of it, the screen does look pretty sharp.
this probably means the resolution is set as it should be.
raise the refresh rate to max and load up a game on the TV.
see what the in-game settings show for resolution.
if 2160 then you're all good.
 
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Solo Popo

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I posted a thread in the Displays forum about a different issue with this TV that wound up having some relevence to this discussion.

 

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