LG 4K 27UK850W USB-C monitor now unable to display 4K via USB-C

Forums › Desktop computing › LG 4K 27UK850W USB-C monitor now unable to display 4K via USB-C - only able to do so using HDMI

turtleattacks

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#289298 26-Aug-2021 19:00

Hi guys,

I have a LG 27uk850-w (https://www.lg.com/us/monitors/lg-27UK850-W-4k-uhd-led-monitor) which has had its panel replaced under warranty once. Apart from that it's fairly trouble free.

I had given this monitor about a year ago to use and I've always noticed that she's been driving it using 1080p, my immediate assumption is that it's just a settings issue.

However today when I sat down and had a look, I realised that we can no longer drive 4k using USB-C. I had been using it for about 2 years driving 4K using USB-C.

I tried 2x Macbook Pros, 1x Windows 10 laptop and 2x USB-C cables - none of would work. It would only deliver power + 1080p.

The USB-C cable seem to work on other 4K USB-C monitors, driving 4K.

HDMi seems to work under 4k for Windows 10 laptop.

Anyone got any ideas?

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RunningMan

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#2767166 26-Aug-2021 19:10

Check the refresh rate being used, and USB port settings on the monitor. If the refresh rate is too high then available resolutions may drop. If the USB C connection needs to allocate bandwidith to a USB 3.x output port then that will reduce bandwidth available for high res/refresh rates. Check the monitor settings to see if USB ports can be dropped to USB 2.0.

turtleattacks

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#2767168 26-Aug-2021 19:15

RunningMan:

Check the refresh rate being used, and USB port settings on the monitor. If the refresh rate is too high then available resolutions may drop. If the USB C connection needs to allocate bandwidith to a USB 3.x output port then that will reduce bandwidth available for high res/refresh rates. Check the monitor settings to see if USB ports can be dropped to USB 2.0.

60Hz and can't be dropped.

(Mac)

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lxsw20

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#2767170 26-Aug-2021 19:21

Is it the original USB-C Cable? I know you said you've tested on other screens, but I've personally found some displays are really really fussy with this.

turtleattacks

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#2767172 26-Aug-2021 19:25

lxsw20:

Is it the original USB-C Cable? I know you said you've tested on other screens, but I've personally found some displays are really really fussy with this.

Don't think the monitor came with USB-C cables, I had to go out and buy one.

It worked fine for about 2 years when I had it. (Can't remember which USB-C cable I used though)

The 2x USB-C Cables are high speed and works on my Dell 32" 4K USB-C monitor no issues.

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RunningMan

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#2767173 26-Aug-2021 19:26

Checking the specs, this doesn't have a USB C input at all. What cables are you using?

turtleattacks

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#2767176 26-Aug-2021 19:34

RunningMan:

Checking the specs, this doesn't have a USB C input at all. What cables are you using?

Sorry, I linked the wrong device. Should be the 850 one.

https://www.lg.com/us/monitors/lg-27UK850-W-4k-uhd-led-monitor

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RunningMan

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#2767179 26-Aug-2021 19:56

That's a fairly big difference.

Settings-General-Displayport 1.2 - is this enabled?

Looks like it automatically drops the monitor USB ports to 2.0 when using USB-C input.

lxsw20

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#2767180 26-Aug-2021 19:57

I had an 850 and it did come with a USB C cable

turtleattacks

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#2767181 26-Aug-2021 19:59

RunningMan:

That's a fairly big difference.

Settings-General-Displayport 1.2 - is this enabled?

Looks like it automatically drops the monitor USB ports to 2.0 when using USB-C input.

Yes, that's enabled.

Should it be on or off?

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RunningMan

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#2767182 26-Aug-2021 20:05

Manual isn't completely clear - I would have thought on, but try turning off just in case.