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

[glennui]

Adding my thanks to joevt and contributing some data to people looking for solutions.

I have the 27MD5KL (2019 LG 5K) and wanted to pair it with my new PC, which is running a Nvidia 3080 Founders Edition. This newer version of the monitor supports video over USB-C.

As a quick fix to see if the most basic of cables would work, I bought the Amazon Basics Bi-Directional USB-C to DisplayPort Cable. I use headphones on this PC, so knew this cable only supplies video, and none of the USB functions of the monitor such as the hub.

✅ It works! It runs at 4K (3840 x 2160) 8bit @ 60Hz automatically. There are a few caveats:

• It doesn't always turn on when I power my PC; once it did pick it up after a minute or two, the other time I had to plug it into my Macbook first, and then swap the cable to my PC.
• Letting the display go to sleep, and then waking it, sees some flickering lines and the monitor trying to correct itself by going to black a few times. So I've set display sleep to disabled, and put a screensaver on.
• When I was launching COD:BO, the game was attempting to go fullscreen at whatever resolution was previously set, and had the above flickering lines and black screens again, while it couldn't resolve itself. I relaunched the game a second time and it successfully adjusted to the resolution correctly, eliminating the problem.

I am using ClickMonitorDDC to control the brightness from my taskbar. It works well enough; hover over the icon and use my mousewheel to raise it up and down. At the back of the monitor I've got both cables tied together so I can swap them when I'm switching between work/gaming.

At some point I may upgrade to a different cable which supports the USB functions—one of the powered cables like the CAC-1332 or SIIG Converter Adapter, but for now I'm happy. Those cables are harder to find and expensive to ship to the UK!

 

[blaraka]

Well, that could be possible in theory if GC-TITAN RIDGE sends both DP streams directly to TB port. But technically 1x PCI-E speed won't be enough for Thunderbolt 3 itself. A am as well not sure about USB connection that it would be recognized by the system.

GC-Titan Ridge does that, puts both DP connections into Thunderbolt that is.

Also, definitely no USB connection, that USB port is a hack for feeding GPUs mining data, I don’t intend to connect it to anything.

There are reports on the internet (from @joevt for example) that GC-Titan Ridge is able to combine DP streams and output them through TB even without TB functionality provided otherwise via PCIe, it’s enough to power it.
I’m not sure though if that riser and power supply would power it correctly. IT-GO case seems not available anywhere saddly.

 

[etc]

GC-Titan Ridge does that, puts both DP connections into Thunderbolt that is.

Also, definitely no USB connection, that USB port is a hack for feeding GPUs mining data, I don’t intend to connect it to anything.

There are reports on the internet (from @joevt for example) that GC-Titan Ridge is able to combine DP streams and output them through TB even without TB functionality provided otherwise via PCIe, it’s enough to power it.
I’m not sure though if that riser and power supply would power it correctly. IT-GO case seems not available anywhere saddly.

I think to get full 5K (two mixed streams) you need TB Bus to be enabled. Otherwise you'll get 4K.

So far I cannot get full 5K in Catalina with TITAN RIDGE. I guess it because I didn't enabled TB Bus and it actually works via USB-C. I think you'll get the same situation.

 

[Mcdevidr]

Just an update the Wacom link connected from my rx5600xt to lg ultra fine 4K started having black out issues where the screen would just disappear on and off. I ended up sending the whole setup back as it was getting annoying.

As for other ways to hook up the display. I tried some really odd setup where I had an egpu hooked up to a dell xps 13 through thunderbolt and then connected the other thunderbolt on the xps to the lg ultra fine and it worked surprisingly. The gpu was even being used to render a game being played on the ultra fine. I’m sure there was a performance hit but didn’t I didn’t test.

 

[joevt]

@joevt
I've seen you discussing those setups over the Internet so I'd like to ask you if you know anything about the probability of following setup working:

- PCIe Riser with 4-pin power input [https://www.amazon.fr/gp/product/B01N42OWYP/ref=ox_sc_act_title_1?smid=A1HHFK55UJVMH4&psc=1]
- Molex 5V power supply [https://www.amazon.fr/gp/product/B00X5WZU0K/ref=ox_sc_act_title_2?smid=A24VGMIX7ES3DX&psc=1]
- GC-Titan-Ridge 2

This would NOT be connected to any actual PC directly. I'd like to feed it with two DP streams out of ThinkPad (it's able to output 4k60Hz DP alt mode out of Thunderbolt 3 ports and 4k60Hz DP alt mode out of USB-C so I'd try to connect it to Titan Ridge with USB-C -> mDP adapters).

It might work. Different Thunderbolt 3 add-in cards work with different risers.
The smallest riser is an M.2 to PCIe x4 (make sure it has voltage regulator for 3.3V so you don't need to connect it to an M.2 slot) https://www.microsatacables.com/pci-e-1x-4x-card-to-m-2-m-key-4-lane-pcie-slot-adapter-m2-921-1x4x
The one that I've had least trouble with is the dual slot one that comes with the IT-GO (also comes with an enclosure) https://www.aliexpress.com/i/32824540969.html (might not come with power supply separately).
I've never tried an LG display before. There may be issues trying to get it to wake - so start testing with non-Thunderbolt display first.
I've never tried the GC-TITAN RIDGE 2.
I have tried Dell UP2715K 5K display with Thunderbolt 3 to dual DisplayPort adapter - which is the next best thing to an LG UltraFine 5K (but the Dell has buttons and an onscreen menu which makes it better).
I have tried GC-ALPINE RIDGE and GC-TITAN RIDGE, both revision one.

Well, that could be possible in theory if GC-TITAN RIDGE sends both DP streams directly to TB port. But technically 1x PCI-E speed won't be enough for Thunderbolt 3 itself. A am as well not sure about USB connection that it would be recognized by the system.

Both DP streams get sent to the TB port (two connections to one port or one connection to each port). Both USB-C DisplayPort alt mode and Thunderbolt DisplayPort tunnelling functionality should work. PCIe devices usually always work no matter the link rate and link width (e.g. a PCIe 4.0 x16 GPU can work at PCIe 1.0 x1). USB won't work without a PCIe connection between the computer and the Thunderbolt 3 add-in card. Even then, you may need software to enable the connection (USB works with GC-TITAN RIDGE without additional software, USB works with GC-ALPINE RIDGE with a small poke before OS startup, PCIe tunnelling requires software - a warm boot from Windows is enough for a GC-TITAN RIDGE, GC-ALPINE RIDGE requires additional software for PCIe tunnelling).

I have the 27MD5KL (2019 LG 5K) and wanted to pair it with my new PC, which is running a Nvidia 3080 Founders Edition. This newer version of the monitor supports video over USB-C.

As a quick fix to see if the most basic of cables would work, I bought the Amazon Basics Bi-Directional USB-C to DisplayPort Cable.

✅ It works! It runs at 4K (3840 x 2160) 8bit @ 60Hz automatically.

10bpc should also work. You can try 5K 30Hz like @blaraka did https://forums.macrumors.com/thread...indows-computers-via-dp.2227756/post-29569370 using a custom resolution:
< 37Hz 10bpc, < 46Hz 8bpc, < 61Hz 6bpc. Actual max refresh rate may be limited by pixel clock rather than DisplayPort 1.2 bandwidth. @blaraka said the max pixel clock that he could get an image from is near 600 MHz (39 Hz). In that case there's no point trying 6bpc except to see if it works.

At some point I may upgrade to a different cable which supports the USB functions—one of the powered cables like the CAC-1332 or SIIG Converter Adapter, but for now I'm happy. Those cables are harder to find and expensive to ship to the UK!

CAC-1332 is HDMI - avoid that unless you don't have DisplayPort such as a gaming console.

So far I cannot get full 5K in Catalina with TITAN RIDGE. I guess it because I didn't enabled TB Bus and it actually works via USB-C. I think you'll get the same situation.

That could be an issue - a solution to force Thunderbolt connection may be to put an Alpine Ridge Thunderbolt device between the GC-TITAN RIDGE and the LG?

Just an update the Wacom link connected from my rx5600xt to lg ultra fine 4K started having black out issues where the screen would just disappear on and off. I ended up sending the whole setup back as it was getting annoying.

Were you using the HDMI or mDP input of the Wacom Link Plus? I think the HDMI input is flaky (and kind of useless since it only supports up to HDMI 1.4; the CAC-1332 is better because it support HDMI 2.0).

As for other ways to hook up the display. I tried some really odd setup where I had an egpu hooked up to a dell xps 13 through thunderbolt and then connected the other thunderbolt on the xps to the lg ultra fine and it worked surprisingly. The gpu was even being used to render a game being played on the ultra fine. I’m sure there was a performance hit but didn’t I didn’t test.

XPS -> eGPU
-> LG
There exists a feature where a GPU can send rendering results to a less powerful GPU for output to a display.

AMD XConnect™ Technology

With AMD XConnect™ Technology it is easier to connect an external Radeon™ graphics card. Portability meets performance with AMD XConnect™ technology.

www.amd.com

Optimus | Technology | GeForce

View the latest GeForce graphics card technology including PhysX, 3D Vision, CUDA, SLI, and more. Increase your GPU power with NVIDIA technology.

www.nvidia.com

 

[blaraka]

It might work. Different Thunderbolt 3 add-in cards work with different risers.
The smallest riser is an M.2 to PCIe x4 (make sure it has voltage regulator for 3.3V so you don't need to connect it to an M.2 slot) https://www.microsatacables.com/pci-e-1x-4x-card-to-m-2-m-key-4-lane-pcie-slot-adapter-m2-921-1x4x
The one that I've had least trouble with is the dual slot one that comes with the IT-GO (also comes with an enclosure) https://www.aliexpress.com/i/32824540969.html (might not come with power supply separately).
I've never tried an LG display before. There may be issues trying to get it to wake - so start testing with non-Thunderbolt display first.
I've never tried the GC-TITAN RIDGE 2.
I have tried Dell UP2715K 5K display with Thunderbolt 3 to dual DisplayPort adapter - which is the next best thing to an LG UltraFine 5K (but the Dell has buttons and an onscreen menu which makes it better).
I have tried GC-ALPINE RIDGE and GC-TITAN RIDGE, both revision one.

Thanks for response!
I might skip that experiment after all. Given where I live (Iceland; everything I order from abroad has VAT+Customs added on top and the resell market is very thin) it just feels like too much of an investment into running 60Hz from not even my laptop (it's from work).

 

[cataclysmicvoid]

So my Club3D CAC-1332 (HDMI 2.0 > USB-C DP 1.2 alt mode) arrived today...

If I plug it* into a 2020 Mac Mini (M1) it gives me:
- 3840 x 2160 (4K) @ 60Hz
- audio works?! (over USB)**
- webcam works?!
- brightness doesn't work

So Club3D was wrong when they told me it doesn't transmit data over USB-C (#207). Naturally, if I plug the USB-A to micro USB adapter power cable into a wall outlet instead of the Mac mini, audio / webcam is gone.

(*Plugged into LG UltraFine 5K 27MD5KL-B via USB-C-to-USB-C (USB 3.1) cable included with monitor.)
(**To my ears the quality sounds worse than I'm used to over Thunderbolt 3, maybe lower bitrate?)

I don't have a PC to test with.

Unfortunately it doesn't work so well for what I bought it for:

Plugged into a Nintendo Switch dock, Switch only offers 480p or 720p output to the monitor. And no audio. Still trying to diagnose this but no leads so far. Makes me wonder if @laurienicholas got 1080p or just 720p onto their UltraFine 4K from the Switch using the Foinnex cable (#156)?

cc/ @x2max @mynamebrody

An update to my earlier post re: Club3D CAC-1332 for anyone interested. (I also suspect the SIIG adapter is the same unit; they look identical physically.)

Firstly, I do wonder if it would be possible to get 4096 x 2160 from the Mac Mini HDMI port (or a PC) using this adapter? It would be a nice boost over "standard" 4K. The adapter claims to support it, but the Mac did not show the option when I tested it.

Using an EDID emulator (e.g. this or this), the Nintendo Switch will pass 1080p through the adapter to the LG 5K properly. It seems the CAC-1332 may have some sort of non-standard EDID implementation that doesn't pass the information along properly.

Connecting a Roku Streaming Stick+ (3810X, 4K) directly to CAC-1332 (via an HDMI female-to-female adapter) is very finicky, not sure I've ever gotten image this way.

Going through an EDID emulator device does work. If I set the emulator to pass-through, the Roku says the monitor/adapter can support 4K@60Hz SDR with HDCP 2.2 — but no image appears if I choose the 60Hz option on the Roku. Most other emulator settings will show image (including 4K@30Hz) but the color is completely off (purple-green, see attachment).

The Ezcoo emulator has a "test" switch — it's not clear what it does — and that will *usually* get the proper colors to show from the Roku. As will using the built-in 4K > 1080p converter setting. I can get 4K@60Hz to show image with this "test" mode, but the color is off again. Maybe if I try enough times it will show the right color, as it does at 30Hz on this setting.

 

[joevt]

Firstly, I do wonder if it would be possible to get 4096 x 2160 from the Mac Mini HDMI port (or a PC) using this adapter? It would be a nice boost over "standard" 4K. The adapter claims to support it, but the Mac did not show the option when I tested it.

I did some tests on my Intel Mac mini 2018 (uses the same DisplayPort to HDMI 2.0 chip that the M1 uses).
I used a CAC-1331 (I guess it uses the same HDMI 2.0 to DisplayPort chip as the CAC-1332).
These are the results:

All timings are CVT-RB unless indicated:

                                      Catalina            Big Sur
3840x2160 60Hz 533.25 MHz             √                   √
3840x2160 60Hz 594.00 MHz HDMI)       √                   wrong colors
3840x2160 65Hz 579.06 MHz             black               

4096x2160 60Hz 567.31 MHz             √                   √
4096x2160 61Hz 577.06 MHz             black
4096x2160 62Hz 586.81 MHz             black
4096x2160 63Hz 596.96 MHz             black

4096x2304 59Hz 594.81 MHz             √                   unstable; eventual panic/restart after a couple minutes

This is not useful for M1 Macs until a method to add custom timings is found unless your display has a working timing already in its EDID (but that does not guarantee that the M1 Mac will accept the timing).

Using an EDID emulator (e.g. this or this), the Nintendo Switch will pass 1080p through the adapter to the LG 5K properly.

It seems those can only copy an EDID. I would like to find devices for DisplayPort 1.4 and HDMI 2.0 that can be programmed with arbitrary EDIDs using a USB serial connection. With arbitrary EDID, you can work around the problem of not being able to add custom timings on M1 Macs.

It seems the CAC-1332 may have some sort of non-standard EDID implementation that doesn't pass the information along properly.

Extract the EDID with and without the CAC-1332 to see what the difference is. Use the AGDCDiagnose command on an Intel Mac or use a PC.

Going through an EDID emulator device does work. If I set the emulator to pass-through, the Roku says the monitor/adapter can support 4K@60Hz SDR with HDCP 2.2 — but no image appears if I choose the 60Hz option on the Roku. Most other emulator settings will show image (including 4K@30Hz) but the color is completely off (purple-green, see attachment).

The Ezcoo emulator has a "test" switch — it's not clear what it does — and that will *usually* get the proper colors to show from the Roku. As will using the built-in 4K > 1080p converter setting. I can get 4K@60Hz to show image with this "test" mode, but the color is off again. Maybe if I try enough times it will show the right color, as it does at 30Hz on this setting.

The colors problem may be an issue with Big Sur? In my testing (shown above) colors were wrong for one of the timings in Big Sur but not in Catalina. This is a RGB/YCbCr mixup.

The black image may be in issue with the timing. The LG UltraFine 5K 27MD5KL has a 4K timing that is neither HDMI nor CVT-RB:
3840x2160@59.999Hz 133.319kHz 522.61MHz h(8 32 40 +) v(1 8 53 -)
You should test the LG UltraFine 5K with an Intel Mac's DisplayPort output to see if it can support arbitrary 4K timings/refresh rates - especially the standard CVT-RB timing and the HDMI timing.

 

[fgengineer]

I managed to score a used lg 5k UltraFine in good condition. It is the older version that only supports thunderbolt.

I also have the new version that does support USB-C. The LG was previously connected to the titan-ridge add-in-card and I got full 5k resolution plus the speaker and webcam working which I was using because of covid.

I currently have both monitors working. The old version 5k is connected to the titan ridge thunderbolt 3. The new version 5k is connected to my video card using the amazon basics DisplayPort to USB-C bidirectional cable. This only gives me a 4k connection.

My video card is a AMD radeon 5700 xt with 3 displayports and 1 hdmi. 2 displayports are connected to the titan ridge card.

Now, my dilemma is how to get both monitors working at 5k resolution. I was thinking of getting another titan ridge card but that would require another video card as well for more displayports. My computer does have an additional 16x pcie free for another video card. It also has an additional 8x pcie slot, but that is covered by my graphics card. I was thinking of getting one of those pcie extenders and connecting the additional titan ridge card that way.

I do have another 4k monitor using up that additional hdmi port.

Any thoughts on best way to achieve this. My suggested solution is pricey and complicated.

 

[joevt]

I managed to score a used lg 5k UltraFine in good condition. It is the older version that only supports thunderbolt.

I also have the new version that does support USB-C. The LG was previously connected to the titan-ridge add-in-card and I got full 5k resolution plus the speaker and webcam working which I was using because of covid.

I currently have both monitors working. The old version 5k is connected to the titan ridge thunderbolt 3. The new version 5k is connected to my video card using the amazon basics DisplayPort to USB-C bidirectional cable. This only gives me a 4k connection.

My video card is a AMD radeon 5700 xt with 3 displayports and 1 hdmi. 2 displayports are connected to the titan ridge card.

Now, my dilemma is how to get both monitors working at 5k resolution. I was thinking of getting another titan ridge card but that would require another video card as well for more displayports. My computer does have an additional 16x pcie free for another video card. It also has an additional 8x pcie slot, but that is covered by my graphics card. I was thinking of getting one of those pcie extenders and connecting the additional titan ridge card that way.

I do have another 4k monitor using up that additional hdmi port.

Any thoughts on best way to achieve this. My suggested solution is pricey and complicated.

Save money and go with 5K 39Hz on the new LG? That should work with a single DisplayPort 1.2 connection. Then get a Wacom Link Plus or Belkin Charge and Sync Cable for USB functionality.

It would be interesting to know if the old LG can work with a single DisplayPort 1.2 connection (try 4K first, then see if it can also do 5K 39Hz).

The W5700 has 6 DisplayPorts. The W5500 has 4 DisplayPorts. You might find a 5700 XT with 4 DisplayPorts (ASRock Radeon RX 5700 XT 8 GB Taichi X OC+)

What motherboard do you have? Any free M.2 slot can be converted to PCIe x4.

 

[fgengineer]

Save money and go with 5K 39Hz on the new LG? That should work with a single DisplayPort 1.2 connection. Then get a Wacom Link Plus or Belkin Charge and Sync Cable for USB functionality.

It would be interesting to know if the old LG can work with a single DisplayPort 1.2 connection (try 4K first, then see if it can also do 5K 39Hz).

The W5700 has 6 DisplayPorts. The W5500 has 4 DisplayPorts. You might find a 5700 XT with 4 DisplayPorts (ASRock Radeon RX 5700 XT 8 GB Taichi X OC+)

What motherboard do you have? Any free M.2 slot can be converted to PCIe x4.

Thanks for the reply.

How do I get the 5k 39 Hz working on the LG?

I have tried looking for the ASRock Radeon RX 5700 XT 8 GB Taichi X OC+ but it is very hard to find and highly overpriced.

The W5700 is an interesting option. You say it has 6 displayports, but I see it listed as 5 displayports and a USB-C output. Can the USB-C output be used as a DisplayPort output as well? Would that mean I would be able to drive 3 5k displays or 2 5k displays and one 6k display ?(For when I get the XDR pro - A guy can dream). With how overpriced GPUs are right now, I could sell my current card and get the W5700 without spending too much money.

I have the Gigabyte TRX40 AORUS PRO WIFI motherboard. I think I have version 1.0 - https://www.gigabyte.com/Motherboard/TRX40-AORUS-PRO-WIFI-rev-10. I am using one of the m.2 slots and should have 2 free slots.

 

[joevt]

How do I get the 5k 39 Hz working on the LG?

In macOS, SwitchResX should allow you to add custom timings. Create a new custom timing, set it to CVT-RB, then enter the width and height and refresh rate. 5120x2880 39Hz. Maybe try other refresh rates like 40Hz - see how high you can go. After creating all the timings you want to test, type Command-S to save, then click the Activate Immediately button.

In Windows, use CRU to add timings to the Display ID extension block. AMD Software has problems with its custom resolution feature, so just use CRU.

The W5700 is an interesting option. You say it has 6 displayports, but I see it listed as 5 displayports and a USB-C output. Can the USB-C output be used as a DisplayPort output as well?

The USB-C port of the W5700 supports USB 3.1 gen 2 and DisplayPort Alt Mode. It can do USB 2.0 + four lanes of DisplayPort 1.4 (like with the LG displays), or USB 3.1 gen 2 + two lanes of DisplayPort 1.4 (like with a USB-C dock such as the CalDigit SOHO).

Would that mean I would be able to drive 3 5k displays or 2 5k displays and one 6k display ?(For when I get the XDR pro - A guy can dream). With how overpriced GPUs are right now, I could sell my current card and get the W5700 without spending too much money.

Yes, probably. Maybe you can even do two 5K and two 6K since the 6K can use DSC.
- three 5K displays (dual DisplayPort 1.2)
- six 4K displays (DisplayPort 1.2)
- six 5K displays (DisplayPort 1.2 for the LG UltraFine 5K at 5K 39Hz, DisplayPort 1.4 for the Iiyama PROLITE XB2779QQS-S1 or similar)
- six 6K display (DisplayPort 1.4 with DSC)

There may be an internal limit in the W5700 or its drivers that limits the number of pixels per second or the total number of pixels, or the number of DSC streams or whatever - no one has tested more than three 5K or 6K displays.

I have the Gigabyte TRX40 AORUS PRO WIFI motherboard. I think I have version 1.0 - https://www.gigabyte.com/Motherboard/TRX40-AORUS-PRO-WIFI-rev-10. I am using one of the m.2 slots and should have 2 free slots.

The motherboard manual will tell you what PCIe/M.2/SATA slots/ports can be used together or not.
ADT.Link has many cables/adapters for PCIe and M.2 http://www.adt.link Check their M.2 selection http://www.adt.link/m2m.html
I don't know if they have a cable that's appropriate for exposing the slot that is under the GPU. The R12SL-FL would be nice if there was a R22SL-FL version but maybe the 13.5 mm height is a couple mm two much to fit under a graphics card? I guess it can be trimmed a couple millimeters if necessary. Maybe the R22SL can be bent 90° (might be difficult if the wires are not soldered on the same line) and trimmed a couple millimeters to fit? Maybe ADT can make a custom R22SL-FL - I've never tried asking for something that's not in their list of products.

 

[cjt782]

Instead of Wacom Link Plus, try Belkin Charge and Sync Cable for HUAWEI VR Glass? It will give brightness control and USB-C ports. Maybe it will fail like the Wacom Link Plus. In that case, maybe a different DisplayLink adapter might work but probably will have same problem as Wavlink dock.

Just wanted to give a brief update, as the Belkin Charge and Sync Cable for HUAWEI VR Glass finally arrived.

Recap of my setup:
2020 MacBook Pro (M1) with 2 LG 4k Ultrafine monitors. I plug directly to one monitor, the other has the WavLink USB Hub with DisplayLink in between.

I was using the Wacom to covert the DisplayPort output from the WavLink back to something the monitor would recognize, but it was a bit spotty and maxed out at 1920x1080@30Hz. It worked more consistently if I plugged the mini-USB cable into a wall instead of the WavLink, but this of course meant sacrificing the USB-C ports and sound on the monitor (they still work to, for example, charge something, but there's no connection to the laptop).

With the Belkin cable, I'm able to get 2048x1152@60Hz consistently, with the USB-C ports functioning as expected. Any higher resolution (even with lower refresh rates) yields a black screen. I do not get brightness control with this setup unfortunately, which might just be a limitation of the WavLink. I do get sound, although I can't really see a scenario where I would use the sound on the 2nd monitor, I'll just use the monitor plugged directly to the laptop.

I might mess around with plugging one or both of the USB-A cables from the Belkin into wall plugs or an adapter on the MacBook directly (not a real solution, but could be interesting) instead of the WavLink. I'll report back if this lets me bump up the resolution or gets brightness control.


Conclusion for anyone else with an M1 trying to get dual USB-C monitors working:

The Belkin cable will get you a better refresh rate, slightly better resolution, and better reliability on reboot/plugging in than the Wacom Link Plus, at the cost of one more USB port, about $20 higher price, and a month of shipping from China.

If you want true dual 4k and/or brightness control, you may need to avoid the M1, try some alternatives to the WavLink, or buy 4k monitors that take DisplayPort or HDMI directly instead of the LG Ultrafine.

 

[joevt]

With the Belkin cable, I'm able to get 2048x1152@60Hz consistently, with the USB-C ports functioning as expected. Any higher resolution (even with lower refresh rates) yields a black screen. I do not get brightness control with this setup unfortunately, which might just be a limitation of the WavLink. I do get sound, although I can't really see a scenario where I would use the sound on the 2nd monitor, I'll just use the monitor plugged directly to the laptop.

Is 2048x1152@60Hz a HiDPI mode (so the actual resolution is 4096x2304)? Is your LG 4K the older 21.5" 4096x2304 USB-C display, or the newer 24" 3840x2160 Thunderbolt display?
The script at https://gist.github.com/joevt/e862b0088ef58b9144877d01401bcee8 will tell you what the output display timing is.

Maybe brightness control is broken because there's something missing that macOS needs to pair the USB brightness control with the display. That's a problem for DisplayLink and/or Apple to solve. People have made software to do brightness control with DDC/CI - I don't know if DisplayLink exposes DDC/CI of a display. Someone could make software that sets brightness control over USB. It could be as simple as a HID device. Anyway, there is USB software on Windows that can capture USB commands. If you do that while using Boot Camp drivers to do brightness control, then you could find out what USB commands are required to do brightness control.

I might mess around with plugging one or both of the USB-A cables from the Belkin into wall plugs or an adapter on the MacBook directly (not a real solution, but could be interesting) instead of the WavLink.

Another alternative is a different USB or Thunderbolt hub or dock for connecting the USB-A cables.

 

[amrd]

Apologies if this has already been answered. I've gone through the 11 pages but am a little overwhelmed.

I have the newer version of the LG Ultrafine 4K Monitor that supports TB3 & USB-C and I'm looking to connect it to my Windows PC. My graphics card (GeForce GTX 1070 - Old, I know) has DisplayPorts that I'm looking to use. Will this bidirectional USB-C to DisplayPort 1.4 Cable by Startech work with my PC? From what I've read this cable-only method works only up to 4K, but that's fine as my monitor is 4K and not 5K. If the speaker and the USB ports on the back of the monitor don't work that is ok with me.

Appreciate any help. Thank you!

 

[chesai]

Can you find a gaming PC that supports a Thunderbolt 3 add-in card that has 2 DisplayPort inputs such as the GC-ALPINE RIDGE or GC-TITAN RIDGE?
Otherwise the solutions are the Wacom Link Plus or Belkin Charge and Sync Cable or Sunix UPD2018 or whatever.
https://egpu.io/forums/gpu-monitor-...sb-c-to-displayport-cable/paged/4/#post-79127

I think Mac <-> LG <-> LG <-> PC could work like below but I'm not sure (I could test with my PC but it's in pieces at the moment)
1) The Mac is controlling the displays and the PC is off.
2) Turn off the Mac
3) Turn on the PC
4) Now the PC is controlling the displays and the Mac.

Hi everyone... I wanted to drop back in and give feedback on the solution that worked for me after getting advice on this thread and from friends.

To recap, I was using two LG 4K displays (the later versions with 2x TB and additional USB-C connectors) daisy-chained with my Mac Book Pro. But I wanted to buy a gaming PC that could also utilise both screens and wanted to be sure this was possible before splurging the cash.

In the end I custom-spec'd a gaming PC from overclockersUK. I deliberately chose a Gigabyte motherboard with thunderbolt headers so that the Titan Ridge 2 was an option, and I chose a matching Gigabyte 3080 GPU with >2 display ports.

When I took delivery, the first thing I tried was connecting the 3080 GPU's display ports directly to the two LG screens with the Amazon Basics bi-directional DP to USB-C cables. Worked absolutely fine. First time I tried, I got some horizontal flashing white lines, but resetting the max resolution in windows and rebooting cured this. It even seems to work in full 4k at 60Hz which the LG manual says it shouldn't. Downsides were having to plug and unplug cables when I wanted to switch from using both screens with the PC to both screens with the MacBook Pro, and no sound obviously from the PC.

So next thing I did was install the Titan Ridge 2.0 thunderbolt adaptor into the PC. This was a bit of a pain -- the thunderbolt headers on the motherboard were hidden away under the GPU and the PSU supply was buried too but eventually it was manageable. Used the two cables that came with the Titan Ridge to connect from two DPs on the 3080 card to the 2 mini-DP ports on the Titan Ridge. Then daisy chained the two LG screens to one of the two Thunderbolt ports on the Titan Ridge. Installed the drivers and it all works perfectly. Still works full 4k at 60 Hz on both screens. No white lines. Sound works (windows even recognises the two screens as separate sound outputs so you can choose which to use). Better still, no more switching cables, I can leave it Mac <-> LG <-> LG <-> PC no problem. When I want the Mac to use both screens I can turn off the PC (or unplug I suppose) and the Mac automatically takes over both screens after 1-2 seconds. If I want to use both screens with the PC again, I just pull the TB/charging cable out the side of the Mac. Once the PC takes over the screens (automatically), I can even plug the Mac back in (still turned on) and it will charge off the thunderbolt connection. The PC even recognises the Mac as an unsupported USB attachment.

I should add the graphics work fluidly across both screens running very demanding games like MS Flight Sim, so doesn't appear there's any bottlenecking anywhere either.

Very happy! Thanks again for the help.

 

[Riviera122]

When using my HDMI to USB-C adapter from SIIG, it only outputs at 720P on my 2014 Mac Mini and 2013 MacBook Air. Anyone know why this is?

 

[joevt]

When using my HDMI to USB-C adapter from SIIG, it only outputs at 720P on my 2014 Mac Mini and 2013 MacBook Air. Anyone know why this is?

Is it 1280x720 60Hz (low resolution) or is it 1280x720 60Hz HiDPI (which is actually 2560x1440 60Hz)?

You should be able to do 2560x1440 60Hz and 4K 30Hz. Use SwitchResX to check the timings available. If those timings are missing, then use SwitchResX to add them.

 

[Riviera122]

Is it 1280x720 60Hz (low resolution) or is it 1280x720 60Hz HiDPI (which is actually 2560x1440 60Hz)?

You should be able to do 2560x1440 60Hz and 4K 30Hz. Use SwitchResX to check the timings available. If those timings are missing, then use SwitchResX to add them.

I think it's low resolution. SwitchResX allows me to go to 2560x1440, but I think it just stretches out the 720p text, making it look pretty blurry:

1080p 16:9 setting using SwitchResX:

Native 720p default (text still looks pixellated and blurry):

On the Mac mini running Big Sur. Could this be a limitation of the cable?

 

[joevt]

I think it's low resolution. SwitchResX allows me to go to 2560x1440, but I think it just stretches out the 720p text, making it look pretty blurry:

1080p 16:9 setting using SwitchResX:

Native 720p default (text still looks pixellated and blurry):

On the Mac mini running Big Sur. Could this be a limitation of the cable?

SwitchResX has a HiDPI column that tells if it is HiDPI or not.
If you double click the resolution, SwitchResX will tell you the timing info of the resolution and if it is scaled.

A 720p low resolution mode looks like this (I am using CVT-RB for pixel clocks):
Pixel Clock: 64 MHz
Active: 1280x720
scanrate: 44 kHz 60 Hz
Scale to: blank

A 720p HiDPI mode (or a 2560x1440 low resolution mode) looks like this:
Pixel Clock: 241 MHz
Active: 2560x1440
Scan rate: 89 kHz 60 Hz
Scale to: blank

A 720p scaled mode looks like this (scaled up to 2560x1440):
Pixel Clock: 241 MHz
Active: 2560x1440
Scan rate: 89 kHz 60 Hz
Scale to: 1280x720

A 2560x1440 mode scaled down to 720p looks like this:
Pixel Clock: 64 MHz
Active: 1280x720
scanrate: 44 kHz 60 Hz
Scale to: 2560x1440

Also in SwitchResX, the Display Information tab has info about the supported Frequency Ranges. It can be overridden, so make sure the max is sufficient (something like 200Hz, 200 kHz, 600 MHz)

 

[sbreeze]

Hey guys,

Thanks for this thread and posting your feedback.

1) For those Windows users using ClickMonitorDDC or ScreenBright, can you also adjust colors in addition to brightness?
2) If using just a "regular" DisplayPort to USB-C cable, would one need to use a USB-A (PC, Host) to USB-C (device, monitor) to get the DDC working, or does DDC "just work" with these DP to USBC cables? Or does one need the Belkin Huawei $90 cable to have video + DDC?
3) Has anyone used these on a Linux machine? If so, have you attempted to control brightness and/or colors via DDC, possibly via ddcutil? Does lsusb show your monitor?

I did find these tools but not sure if they'll work:

- https://github.com/rockowitz/ddcutil
- https://github.com/ycsos/LG-ultrafine-brightness
- https://github.com/unknownzerx/lguf-brightnesss

 

[a+macrumors]

Hi everyone... I wanted to drop back in and give feedback on the solution that worked for me after getting advice on this thread and from friends.

To recap, I was using two LG 4K displays (the later versions with 2x TB and additional USB-C connectors) daisy-chained with my Mac Book Pro. But I wanted to buy a gaming PC that could also utilise both screens and wanted to be sure this was possible before splurging the cash.

In the end I custom-spec'd a gaming PC from overclockersUK. I deliberately chose a Gigabyte motherboard with thunderbolt headers so that the Titan Ridge 2 was an option, and I chose a matching Gigabyte 3080 GPU with >2 display ports.

When I took delivery, the first thing I tried was connecting the 3080 GPU's display ports directly to the two LG screens with the Amazon Basics bi-directional DP to USB-C cables. Worked absolutely fine. First time I tried, I got some horizontal flashing white lines, but resetting the max resolution in windows and rebooting cured this. It even seems to work in full 4k at 60Hz which the LG manual says it shouldn't. Downsides were having to plug and unplug cables when I wanted to switch from using both screens with the PC to both screens with the MacBook Pro, and no sound obviously from the PC.

So next thing I did was install the Titan Ridge 2.0 thunderbolt adaptor into the PC. This was a bit of a pain -- the thunderbolt headers on the motherboard were hidden away under the GPU and the PSU supply was buried too but eventually it was manageable. Used the two cables that came with the Titan Ridge to connect from two DPs on the 3080 card to the 2 mini-DP ports on the Titan Ridge. Then daisy chained the two LG screens to one of the two Thunderbolt ports on the Titan Ridge. Installed the drivers and it all works perfectly. Still works full 4k at 60 Hz on both screens. No white lines. Sound works (windows even recognises the two screens as separate sound outputs so you can choose which to use). Better still, no more switching cables, I can leave it Mac <-> LG <-> LG <-> PC no problem. When I want the Mac to use both screens I can turn off the PC (or unplug I suppose) and the Mac automatically takes over both screens after 1-2 seconds. If I want to use both screens with the PC again, I just pull the TB/charging cable out the side of the Mac. Once the PC takes over the screens (automatically), I can even plug the Mac back in (still turned on) and it will charge off the thunderbolt connection. The PC even recognises the Mac as an unsupported USB attachment.

I should add the graphics work fluidly across both screens running very demanding games like MS Flight Sim, so doesn't appear there's any bottlenecking anywhere either.

Very happy! Thanks again for the help.

hey, this sounds amazing!

could you please share your whole setup?

I made the mistake of not getting a TB_HEAD supported motherboard for my ATX + AMD Ryzen 9 5900x + RTX 3070 setup and now considering returning the mobo to get ASRock x570 Creator (or maybe something else, I'm open for suggestions).

my 2nd Generation Ultrafine 5K works OK (4K@60Hz, USB/audio/webcam go brrr) with Moshi bi-directional (I really don't like its' color, the only white thing on my all-black setup) yet I'm willing to get a second 5K or a 4K for daisy chain.

I guess I can't make the daisy chain work without using TB3.

 

[joevt]

2) If using just a "regular" DisplayPort to USB-C cable, would one need to use a USB-A (PC, Host) to USB-C (device, monitor) to get the DDC working, or does DDC "just work" with these DP to USBC cables? Or does one need the Belkin Huawei $90 cable to have video + DDC?
3) Has anyone used these on a Linux machine? If so, have you attempted to control brightness and/or colors via DDC, possibly via ddcutil? Does lsusb show your monitor?

DDC works over DisplayPort, whether the display uses USB-C or not.

USB (Belkin Charge and Sync Cable or Wacom Link Plus or whatever) is required if you want to use USB instead of DDC or if you want to use the USB features of the display such as audio, USB ports, camera, etc.

I did find these tools but not sure if they'll work:

- https://github.com/rockowitz/ddcutil
- https://github.com/ycsos/LG-ultrafine-brightness
- https://github.com/unknownzerx/lguf-brightness

The first one can use DDC or USB.
The second two options use USB. Good find! Maybe they can be ported to macOS for people using DisplayLink where the brightness control doesn't appear in the macOS preferences panel.

 

[Riviera122]

I did find these tools but not sure if they'll work:

- https://github.com/rockowitz/ddcutil
- https://github.com/ycsos/LG-ultrafine-brightness
- https://github.com/unknownzerx/lguf-brightnesss

I use the "up-to-date" version of the bottom one (https://github.com/csujedihy/LG-Ultrafine-Brightness) on W10 and it works great. I've created a shortcut mapped to the brightness key on my Mac keyboard so that if I'm in a full screen app I can adjust the brightness on the fly.

 

[sbreeze]

So I'm following up for the general audience at large. Sorry for the longish post.

Good: I bought an new UltraFine 4K monitor and used the Amazon Basics bidirectional DP/USB-C adapter (6ft) and got it working on Linux PC & Windows PCs via DP, nVidia Quadro Graphics. A few times the DP cable needed plugging / unplugging from the PC end before the LG monitor came up. Once it did, DPMS (powersavings) worked fine, and it wakes up from sleep quickly.

Bad (1): The white point is fixed from the factory and neither DDCutil or ClickMonitorDDC could adjust the color channels, contrast, etc, ONLY the brightness can be controlled. You CANNOT adjust the R/G/B values using any of the "known" methods, I'm sure the LG factory has some tools that can do it.

I suspect in macOS if you change the white point, you're really only changing the video card LUT, but I'm not 100% certain of this. I do have recent USB-C Macbook to test with but not sure how to prove / disprove this.

More info: It's VCP-code 10 in DDC parlance that you use to adjust the brightness. ClickMonitor & DDCUtil could adjust the R/G/B offsets for ALL other monitors I tried (Dell, Viewsonic, Lenovo).

I went ahead and used DispalCAL GUI & my ColorMunki and iDisplay1 to profile the LG and it looks like the white point is set around 6500K and has good calibration from the factory. I can post the color gamut for those interested.

Bad (2): This monitor really suffers from mermism -- the color of the screen shifts very significantly if you're even slightly off axis, horizontal or vertical. If you're looking at web page content or on a typical white/grey background it is VERY noticable. If you're working with a dark color scheme and/or primarily doing image editing or video this monitor has oustanding colors, saturation, black levels and image uniformity. I have a lot of LCDs in my work environment that I did A/B testing with against the LG and none of them showed this level of mermism ; usually the brightness would fall of from oblique angles. But the "pop" you get from looking at images or video content (on this LG) could not be rivaled by anything else I have access to.

So, I conclude this monitor is really for those people working with media and less suited for "general purpose" work which is REALLY disappointing. My need was a 80/20 split between development work (80%, text editors, web pages, etc) and only 20% graphics which has me leaning towards returning it.

Most of the new monitors you can buy these days have VERY poor brightness uniformity and the left/right sides or top/bottom show blue colors or light fall off -- LG has the brightness uniformity perfect across this monitor. For reference, I did try the LG 4K/24" non-Apple model and while the sharpness was amazing, the brightness in general was terrible and uniformity was absurdly poor.

Sigh, back to the drawing board. .