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LG UltraFine 4K and 5K: Yes you can connect it to Windows computers via DP!!!

DeanLubaki

Contributor
Original poster
May 29, 2014
1,082
997
Toronto
Hello everyone,

I have owned the LG Ultrafine 4k for a few days, since the COVID-19 pandemic made work from home mandatory for most Canadians. I love the display, but was struggling to connect it to my work laptop (which doesn’t have USB-C).
After hours of research, 7 different adapters, I finally found the one.

The Wacom Link Plus for Cintiq Pro 13/16 (ACK42819) takes the Mini Display Port signal from your Windows computer and convert it to a USB-C DP-Alt mode signal that your LG UltraFine will recognize.
This adapter even has a supplemental USB Micro-B to USB-A cable that you can connect to your Windows computer so that the speaker work.
The brightness controls also do show up in the Device Manager, so there might be a way of making it work, but unfortunately I cannot tinker with that since I do not have the admin privileges of my work laptop.
The display controls such as brightness can be controlled by this Windows app. It doesn't require that the Micro-B USB cable be plugged to the Wacom, as it uses the DCC protocol over DisplayPort.
The LG Display remembers the brightness from your Mac so you can control it from there by disconnecting the Windows laptop and connecting it to your Mac if like me you cannot install the app on your work computer.

Below is a picture of how you need to plug the Wacom!
Wacom Adapter for LG Ultrafine.jpg

Note that the HDMI port will not work. Also the UltraFine 4K will work at full resolution, but the UltraFine 5K (2019 and later) will max out at 4K.

Cheers!
 
Last edited:

joevt

macrumors 68030
Jun 21, 2012
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The HDMI input is not terribly useful unless you're ok with 4K 30 Hz or 1440p 60 Hz max. Can the LG UltraFine 4K do 30 Hz?

HDMI 2.0 4K 60Hz to DisplayPort converters are much more expensive than the HDMI 1.4 (4K 30 Hz) variety:
 
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joevt

macrumors 68030
Jun 21, 2012
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According to the user manual, yes.
There is a contradiction between page 28 (48 Hz) and page 30 (30 Hz).

The EDID of the old LG UltraFine 4K (product ID 5b10) lists timings for 4096x2304 at 30Hz, 48Hz, and 60Hz and 3840x2160 at 30Hz and 60Hz.

I don't have the EDID for the new LG UltraFine 4K (I think it's product ID 5b7b). You can get that with the AGDCDiagnose command (google for proper usage).
 
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DeanLubaki

Contributor
Original poster
May 29, 2014
1,082
997
Toronto
There is a contradiction between page 28 (48 Hz) and page 30 (30 Hz).

It's not a contradiction. You're reading on page 28 the Resolution and Video Signal rows as if they were related but they're not. The Resolution row simply states that maximum and recommended resolution while the Video Signal row states the range of the refresh rate the monitor supports.
It's only on page 30 that it states which pairings of resolutions and refresh rates are supported.
 
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joevt

macrumors 68030
Jun 21, 2012
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It's not a contradiction. You're reading on page 28 the Resolution and Video Signal rows as if they were related but they're not. The Resolution row simply states that maximum and recommended resolution while the Video Signal row states the range of the refresh rate the monitor supports.
It's only on page 30 that it states which pairings of resolutions and refresh rates are supported.
I was refering to the row on page 28 that says "Video Signal: Vertical Frequency: 48 Hz to 60 Hz"
 
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joevt

macrumors 68030
Jun 21, 2012
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Is that not as sharp as the iMac 27'' 5k monitor?
Do you mean dots per inch?

d = diagonal dimension
x = display width
x*9/16 = display height

d^2 = x^2 + (x*9/16)^2 = x^2 + 81/256 x^2 = 337/256 x^2
x^2 = 256/337 d^2
x = 16/√337 d

iMac = 27" diagonal, x = 23.532539502362831
5120 / x = 218 dpi

LG UltraFine 4K 23.7" diagonal, x = 20.656340229851818
3840 / x = 185 dpi

I think the iMac display has more dots per inch and more inches.
 
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DeanLubaki

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May 29, 2014
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Macdude2010

macrumors 65816
Mar 17, 2010
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The Apple Store
I'm wondering if this would be able to connect an eGPU to the Ultrafine 4k on the Mac side too. Is there anyone that could confirm this works?
 
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joevt

macrumors 68030
Jun 21, 2012
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I'm wondering if this would be able to connect an eGPU to the Ultrafine 4k on the Mac side too. Is there anyone that could confirm this works?
Why wouldn't it work? DisplayPort from eGPU is the same as DisplayPort from Mac.
 
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joevt

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Jun 21, 2012
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well i just foundDelock DisplayPort Adapter for a USB Type-C™ monitor 4K 60 Hz https://www.delock.com/produkte/G_63928/merkmale.html It could use USB c as the output port like this.
Do you think this is also going to work?
That's interesting. It's not bidirectional but it does say 4 or 5 times on that product web page that it works in the direction that is needed for the LG UltraFine 4K. It supports 4K 60Hz which means it is limited to HBR2 link rate. That's enough for the LG UltraFine 4K display. There are better solutions that support HBR3 link rate for DisplayPort 1.3/1.4 displays.

The Delock 63928 adapter doesn't include USB 2.0 input, so it probably won't work for the first generation (21") LG UltraFine 4K display but it should be ok for the 24" LG UltraFine 4K.
 
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Yuyang Wu

macrumors newbie
Apr 23, 2020
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2
doesn't include USB 2.0 input
what's the relationship between USB 2.0 and DisplayPort Adapter for a USB Type-C? The monitor uses the only USB 3.1 port for video and audio transit, and the rest three USB 2.0 just for data and power outlet.
 
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joevt

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Jun 21, 2012
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USB-C DisplayPort alt mode for USB-C displays or USB-C docks or USB-C adapters can have four lanes of DisplayPort and USB 2.0 or two lanes of DisplayPort and USB 3.x.

The LG UltraFine 4K display uses four lanes of DisplayPort 1.2 and USB 2.0. The original 21" LG UltraFine 4K display did not work without a USB 2.0 connection (it wouldn't power on or something).

Some USB-C displays like the ASUS MB169C+ that don't have a power supply require USB for power.
 
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DeanLubaki

Contributor
Original poster
May 29, 2014
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Toronto
what's the relationship between USB 2.0 and DisplayPort Adapter for a USB Type-C? The monitor uses the only USB 3.1 port for video and audio transit, and the rest three USB 2.0 just for data and power outlet.
USB-C DisplayPort alt mode for USB-C displays or USB-C docks or USB-C adapters can have four lanes of DisplayPort and USB 2.0 or two lanes of DisplayPort and USB 3.x.

The LG UltraFine 4K display uses four lanes of DisplayPort 1.2 and USB 2.0. The original 21" LG UltraFine 4K display did not work without a USB 2.0 connection (it wouldn't power on or something).

Some USB-C displays like the ASUS MB169C+ that don't have a power supply require USB for power.

Yup, it is rumoured that only the DP-alt mode signal is not sufficient for the LG UltraFine to turn on. I remember reading on some obscure forum that apparently some sort of USB signal need to also be injected, which is apparently the reason why the HDMI port of the Wacom adapter doesn't work.
It's worth trying! I did have to try 7 different adapters before finding one that worked ¯\_(ツ)_/¯
 
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jessetrippe

macrumors newbie
May 9, 2015
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0
This is awesome. I'm in a similar boat as you (brought the monitor to work from home). One question - will this adapter work with HDMI for both audio and video? I'm interested in connecting a PS4 so I can game and not takeover the TV.
 
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DeanLubaki

Contributor
Original poster
May 29, 2014
1,082
997
Toronto
This is awesome. I'm in a similar boat as you (brought the monitor to work from home). One question - will this adapter work with HDMI for both audio and video? I'm interested in connecting a PS4 so I can game and not takeover the TV.

I haven't been able to make the HDMI port work, and I have no recollection of anyone succeeding either :(
 
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joevt

macrumors 68030
Jun 21, 2012
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The HDMI port of the Wacom Link Plus is HDMI 1.4 (4K 30Hz) and wasn't reliable for me.

There are many cheap HDMI 1.4 to DisplayPort 1.2 adapters that you could use instead.

Club 3d has a new HDMI 2.0 to DisplayPort 1.2 adapter which I think is much cheaper than the ones from SIIG or Gofanco.
 
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PierP

macrumors newbie
May 17, 2020
2
0
Hi everyone,
I tried the setup as suggested with my Lenovo X1 carbon 4th gen, but surprisingly only the audio works, meaning that I can hear some sounds from the monitor but no video. Besides connecting the cable according to the scheme is there something else that I must do to make it works? Thanks in advance!
 
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planetb00m

macrumors newbie
Jan 23, 2020
11
0
Hi everyone,
I tried the setup as suggested with my Lenovo X1 carbon 4th gen, but surprisingly only the audio works, meaning that I can hear some sounds from the monitor but no video. Besides connecting the cable according to the scheme is there something else that I must do to make it works? Thanks in advance!

Hoping this isn't a hardware limitation as I have just bought the same adaptor to use with my works Lenovo laptop.

Is the hub being powered by anything? I've watched a few videos and there is a second usb-c port that is meant to be used to provide power to the HUB.
 
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