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

[danieledone]

Hey everybody, I am new to this forum! I hope you can help me because I am a little bit lost on getting the LG Ultrafine 4k (22MD4KA-B) to work properly on Big Sur and MacBook Pro 2016 with Radeon RX450).
I have been struggling with the following issue:

- the screen shows all the resolutions no problem, but there is no brightness slider whatsoever. I have tried plugging the monitor through the thunderbolt 3 port of the MBP, using TB3 cable, USB-C cable (Using the usb-c LG cable included in the 27 inch 5k LG ultrafine monitor which I also own), TB3 to DisplayPort cable (to a Targus DOCK570EUZ dock in f station), and also Without any other monitor plugged in and with the others, and I can get the full 4096x2304 @60Hz res on all the tests, however the brightness cannot be changed. The monitor is stuck tonmaximu. Brightness and it really is bright - sears my eyes after about one minute lol!

I also have tried adding a second usb cable to the dock as well as to the MBP directly, when trying the docking through usb-c to DP on the targus, as I had read that sometimes controls require a separate usb-c data link, but still no change on that front. No brightness slider is present - see pics. The only way I finally succeeded is by using a TB3 very short cable to the top right TB3 port of the MBP, the slider showed up, I lowered the resolution and then plugged it again in the usual way (through the Targus Dock); the slider disappeared but the brightness setting remained - bizarre!

- the second issue is related to something quite strange I noticed when the system is on screen saver or in operation: the MBP screen and the 5k screen all show the screen saver to be quite smooth and operation and mo loving windows and writing etc is very smooth, whereas the 22MD4KA-B is very very stuttering with a frame transition every 3 seconds which basically makes it unusable as if for example you give a scroll command on a document, it takes almost 2 seconds for the screen to react. SwitchresX and the display properties both show 60Hz refresh, so I am not sure how it could be so stuttering and laggy? Any idea?

Thanks so much in advance!
D

 

[danieledone]

Hey everybody, I am new to this forum! I hope you can help me because I am a little bit lost on getting the LG Ultrafine 4k (22MD4KA-B) to work properly on Big Sur and MacBook Pro 2016 with Radeon RX450).
I have been struggling with the following issue:

- the screen shows all the resolutions no problem, but there is no brightness slider whatsoever. I have tried plugging the monitor through the thunderbolt 3 port of the MBP, using TB3 cable, USB-C cable (Using the usb-c LG cable included in the 27 inch 5k LG ultrafine monitor which I also own), TB3 to DisplayPort cable (to a Targus DOCK570EUZ dock in f station), and also Without any other monitor plugged in and with the others, and I can get the full 4096x2304 @60Hz res on all the tests, however the brightness cannot be changed. The monitor is stuck tonmaximu. Brightness and it really is bright - sears my eyes after about one minute lol!

I also have tried adding a second usb cable to the dock as well as to the MBP directly, when trying the docking through usb-c to DP on the targus, as I had read that sometimes controls require a separate usb-c data link, but still no change on that front. No brightness slider is present - see pics. The only way I finally succeeded is by using a TB3 very short cable to the top right TB3 port of the MBP, the slider showed up, I lowered the resolution and then plugged it again in the usual way (through the Targus Dock); the slider disappeared but the brightness setting remained - bizarre!

- the second issue is related to something quite strange I noticed when the system is on screen saver or in operation: the MBP screen and the 5k screen all show the screen saver to be quite smooth and operation and mo loving windows and writing etc is very smooth, whereas the 22MD4KA-B is very very stuttering with a frame transition every 3 seconds which basically makes it unusable as if for example you give a scroll command on a document, it takes almost 2 seconds for the screen to react. SwitchresX and the display properties both show 60Hz refresh, so I am not sure how it could be so stuttering and laggy? Any idea?

Thanks so much in advance!
D

Apologies, the GPU is the Radeon Pro 560, 4GB RAM. MBP model is shown as MacBook Pro (15-inch, 2017), 2.9GHz Quad-Core Intel i7, 16GB RAM @2133MHz. The other screens work very well attached to it, just this one seem to be stuttering so much and without the brightness control easily accessible.

 

[chesai]

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.

The PC's motherboard is a Gigabyte Z490 Aorus Master, the GPU is a Gigabyte 3080 Gaming OC, and the TB card is a Gigabyte Titan Ridge 2.0. Beware the TB add-in card needs a LOT of connections. It HAS to go into a 4x PCIe slot, there are two TB cables to connect to the MB, plus a USB connector to the MB, plus a double headed power cable to the PSU.

 

[joevt]

Apologies, the GPU is the Radeon Pro 560, 4GB RAM. MBP model is shown as MacBook Pro (15-inch, 2017), 2.9GHz Quad-Core Intel i7, 16GB RAM @2133MHz. The other screens work very well attached to it, just this one seem to be stuttering so much and without the brightness control easily accessible.

- The USB 2.0 header connector is required only if you want to connect a USB 2.0 device to the add-in card.
- The two 6-pin power cables are required only if you want to charge a laptop connected to the add-in card.
- The TB cables are not required in all cases. For example, people use Thunderbolt add-in cards with motherboards that don't have the Thunderbolt headers. But if your motherboard has the header then you might as well use it.

 

[joevt]

Hey everybody, I am new to this forum! I hope you can help me because I am a little bit lost on getting the LG Ultrafine 4k (22MD4KA-B) to work properly on Big Sur and MacBook Pro 2016 with Radeon RX450).
I have been struggling with the following issue:

- the screen shows all the resolutions no problem, but there is no brightness slider whatsoever. I have tried plugging the monitor through the thunderbolt 3 port of the MBP, using TB3 cable, USB-C cable (Using the usb-c LG cable included in the 27 inch 5k LG ultrafine monitor which I also own), TB3 to DisplayPort cable (to a Targus DOCK570EUZ dock in f station), and also Without any other monitor plugged in and with the others, and I can get the full 4096x2304 @60Hz res on all the tests, however the brightness cannot be changed. The monitor is stuck tonmaximu. Brightness and it really is bright - sears my eyes after about one minute lol!

I also have tried adding a second usb cable to the dock as well as to the MBP directly, when trying the docking through usb-c to DP on the targus, as I had read that sometimes controls require a separate usb-c data link, but still no change on that front. No brightness slider is present - see pics. The only way I finally succeeded is by using a TB3 very short cable to the top right TB3 port of the MBP, the slider showed up, I lowered the resolution and then plugged it again in the usual way (through the Targus Dock); the slider disappeared but the brightness setting remained - bizarre!

- the second issue is related to something quite strange I noticed when the system is on screen saver or in operation: the MBP screen and the 5k screen all show the screen saver to be quite smooth and operation and mo loving windows and writing etc is very smooth, whereas the 22MD4KA-B is very very stuttering with a frame transition every 3 seconds which basically makes it unusable as if for example you give a scroll command on a document, it takes almost 2 seconds for the screen to react. SwitchresX and the display properties both show 60Hz refresh, so I am not sure how it could be so stuttering and laggy? Any idea?

Apologies, the GPU is the Radeon Pro 560, 4GB RAM. MBP model is shown as MacBook Pro (15-inch, 2017), 2.9GHz Quad-Core Intel i7, 16GB RAM @2133MHz. The other screens work very well attached to it, just this one seem to be stuttering so much and without the brightness control easily accessible.

The Targus DOCK570EUZ uses DisplayLink. Is the Targus DOCK570EUZ a USB dock or a Thunderbolt dock? I think it's only USB. It has a USB-C port labeled "UP" with a fake Thunderbolt icon. It has USB 3.0 ports, which means if any of the DisplayPort or HDMI ports were connected to GPU, they could only support 4K 30Hz. Since they support 4K 60Hz, they must all use DisplayLink.

Are any of the DisplayPort or HDMI outputs connected to the GPU or are they all DisplayLink?

An LG display connected via DisplayLink will not have Brightness control appear in the Displays preferences panel and the brightness control keys of the keyboard will not work.

DisplayLink uses video compression over USB. It will not be as smooth as a real connection to the GPU.

Use the following command to gather info:
system_profiler SPThunderboltDataType SPUSBDataType SPPCIDataType SPDisplaysDataType > systemprofiler.txt
Use the Finder to compress the result and post it here.

 

[chesai]

- The USB 2.0 header connector is required only if you want to connect a USB 2.0 device to the add-in card.
- The two 6-pin power cables are required only if you want to charge a laptop connected to the add-in card.
- The TB cables are not required in all cases. For example, people use Thunderbolt add-in cards with motherboards that don't have the Thunderbolt headers. But if your motherboard has the header then you might as well use it.

I connected everything and, interestingly, I find the spare 2nd thunderbolt port on the titan ridge to be a much more stable connection for my oculus link that the motherboard's own usb-c port... could be the power supply (?).

 

[Amethyst1]

So I have finally gotten my hands on the 21.5" UltraFine 4K (I have wanted one to play around with for quite some time) and spent the evening hooking it up to a couple of older machines - here are my initial results FWIW. The Wacom Link Plus was used to go from Mini-DisplayPort to USB-C.

Late 2010 11" MacBook Air (NVIDIA GeForce 320M)

- OS X El Capitan (10.11.6): driven at 4096×2304 30 Hz (confirmed via SwitchResX); came up in 2048×1152 HiDPI automatically; built-in speakers work; no brightness control or camera

Early 2011 13" MacBook Pro (Intel HD 3000)

- OS X Snow Leopard (10.6.8): kernel panic
- OS X Mountain Lion (10.8.5): only works at 640×480 (which was oddly stretched)
- OS X Mavericks (10.9.5): only works at 640×480 (which was oddly stretched)

Late 2013 15" MacBook Pro Retina (Intel Iris Pro)

- OS X Mavericks (10.9.5): driven at 4096×2304 48 Hz 3840×2160 60 Hz (confirmed via SwitchResX); came up in 3840×2160 HiDPI (!); other HiDPI modes selectable via RDM or SwitchResX; built-in speakers work, no brightness control

 

[joevt]

So I have finally gotten my hands on the 21.5" UltraFine 4K (I have wanted one to play around with for quite some time) and spent the evening hooking it up to a couple of older machines - here are my initial results FWIW. The Wacom Link Plus was used to go from Mini-DisplayPort to USB-C.

Late 2010 11" MacBook Air (NVIDIA GeForce 320M)

- OS X El Capitan (10.11.6): driven at 4096×2304 30 Hz (confirmed via SwitchResX); came up in 2048×1152 HiDPI automatically; built-in speakers work; no brightness control or camera

Audio is going through USB?
Speakers work because USB audio is a standard that's been around since USB existed. Maybe Brightness control and camera driver for this display don't exist in El Capitan?
Some 21.5" UltraFine 4K displays are manufactured April 2016 (check your EDID). When did the first 21.5" UltraFine 4K come out? https://en.wikipedia.org/wiki/Apple_displays#LG_UltraFine says November 2016.
El Capitan started Sep 2015. 10.11.6 was released Sep 2016. The last update was July 2018.
Maybe the camera and brightness control work in Sierra (September 2016 - September 2019) or High Sierra (September 2017 - November 2020)?

Early 2011 13" MacBook Pro (Intel HD 3000)

- OS X Snow Leopard (10.6.8): kernel panic

Weird. Which kext crashed? Did you try without the USB connection?

- OS X Mountain Lion (10.8.5): only works at 640×480 (which was oddly stretched)
- OS X Mavericks (10.9.5): only works at 640×480 (which was oddly stretched)

Weird. The EDID of the display has modes built-in for 1080p and 1440p. One of them should be usable. Is the GPU working? Did you try adding modes using SwitchResX?
1920x1080@60Hz
2560x1440@60Hz
3360x1890@60Hz
3840x2160@30Hz
3840x2160@60Hz
4096x2304@30Hz
4096x2304@48Hz
4096x2304@60Hz

Late 2013 15" MacBook Pro Retina (Intel Iris Pro)

- OS X Mavericks (10.9.5): driven at 4096×2304 48 Hz (confirmed via SwitchResX); came up in 3840×2160 HiDPI (!); other HiDPI modes selectable via RDM or SwitchResX; built-in speakers work, no brightness control or camera

Does 3840×2160 HiDPI mean 7680x4320 scaled down to 4096×2304?

 

[Amethyst1]

Thanks for your reply!

Audio is going through USB?

Yes.

Some 21.5" UltraFine 4K displays are manufactured April 2016 (check your EDID).

Mine is manufactured week 12 of 2016.

Maybe the camera and brightness control work in Sierra (September 2016 - September 2019) or High Sierra (September 2017 - November 2020)?

Uhhh... Errr... It occurred to me that the 21.5" UF doesn't have a camera. Sorry! So it's just the brightness control. Since 10.12.1 is listed as the minimum required macOS version, I expect it to work on Sierra and up. Maybe I can identify the kext that enables it and inject it into El Capitan? (When I used an acrylic Cinema Display with Mavericks, I had to inject a kext from Mountain Lion to re-enable brightness control.)

2011 MBP - Snow Leopard

Weird. Which kext crashed? Did you try without the USB connection?

Here's the relevant excerpt from the panic log. As for the USB connection, I haven't tried without it yet as I read somewhere the monitor requires USB to be present to fire up.

Kernel Extensions in backtrace (with dependencies):
         com.apple.driver.AppleIntelSNBGraphicsFB(6.3.8)@0xffffff7f80f04000->0xffffff7f80f31fff
            dependency: com.apple.iokit.IOACPIFamily(1.3.0)@0xffffff7f80809000
            dependency: com.apple.iokit.IOPCIFamily(2.6.6)@0xffffff7f8081d000
            dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0xffffff7f80853000
         com.apple.iokit.IOGraphicsFamily(2.2.1)@0xffffff7f80853000->0xffffff7f8087afff
            dependency: com.apple.iokit.IOPCIFamily(2.6.6)@0xffffff7f8081d000

2011 MBP - Mountain Lion / Mavericks

Is the GPU working?

The 13" 2011 MBP doesn't have a discrete GPU, only the integrated HD3000. This one works fine, and I can drive a Dell P2415Q at 3840×2160 and 30 Hz via Displayport (in Snow Leopard as well).

2013 MBP - Mavericks

Does 3840×2160 HiDPI mean 7680x4320 scaled down to 4096×2304?

Yes.

Update: No - the 15" rMBP is actually only driving it at 3840×2160 60 Hz on Mavericks (10.9.5); adding a 4096×2304 48 Hz mode in SwitchResX didn't work.

 

[joevt]

2011 MBP - Snow Leopard

Here's the relevant excerpt from the panic log.

Kernel Extensions in backtrace (with dependencies):
         com.apple.driver.AppleIntelSNBGraphicsFB(6.3.8)@0xffffff7f80f04000->0xffffff7f80f31fff
            dependency: com.apple.iokit.IOACPIFamily(1.3.0)@0xffffff7f80809000
            dependency: com.apple.iokit.IOPCIFamily(2.6.6)@0xffffff7f8081d000
            dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0xffffff7f80853000
         com.apple.iokit.IOGraphicsFamily(2.2.1)@0xffffff7f80853000->0xffffff7f8087afff
            dependency: com.apple.iokit.IOPCIFamily(2.6.6)@0xffffff7f8081d000

SNB stands for Sandy Bridge which is the CPU with the Intel HD 3000 graphics. If the problem is with resolutions >= 4096 in width, then maybe you can eliminate the kernel panic by creating an EDID override and removing the 4096x2304 options. SwitchResX doesn't have an option to remove timings so you'll have to do it manually.
https://gist.github.com/joevt/32e5efffe3459958759fb702579b9529
I don't think I've ever tried 4K in Snow Leopard.

2011 MBP - Mountain Lion / Mavericks

The 13" 2011 MBP doesn't have a discrete GPU, only the integrated HD3000. This one works fine, and I can drive a Dell P2415Q at 3840×2160 and 30 Hz via Displayport (in Snow Leopard as well).

So you're not experiencing the "only works at 640×480" problem anymore?

 

[Amethyst1]

I don't think I've ever tried 4K in Snow Leopard.

I have 3840×2400 working in Mac OS 9.2.2 and OS X Puma (10.1.5). That's an IBM T221on an ATI Mobility Radeon 7500.

So you're not experiencing the "only works at 640×480" problem anymore?

Not with the Dell P2415Q (3840×2160) or IBM T221 (3840×2400). Still present with the UltraFine.

I'll do some more testing later and report back.

 

[joevt]

I have 3840×2400 working in Mac OS 9.2.2 and OS X Puma (10.1.5). That's an IBM T221on an ATI Mobility Radeon 7500.

3840x2400 is a 16:10 aspect ratio - I've never thought about a 4K sized 16:10 display... Apple has 16:10 displays using lower resolutions - old Apple displays and old and new Apple laptop displays (1280x800, 1440x900, 1920x1200, 2560x1600, 2880x1800).

3840x2400@13Hz is between 123 and 152 MHz which is under the limit for single link DVI for 8bpc RGB. I guess this is a single tile mode.
Does Apple support 13 Hz in newer macOS versions?

Do you have the DG1, DG3, or DG5 model?

Wikipedia says the DG1/DG3 display has four 960×2400 stripes. Can macOS see the display as more than one connection using multiple DVI inputs? Wikipedia says it can use single, double, and quad-link for 13, 25, 41Hz (or 17.1, 33.72, and 41Hz with reduced blanking periods).

The DG5 can do:
1) 24 - 25Hz with one dual link tile
2) 48Hz using one dual link tile of 2624×2400 and a single link tile of 1216×2400
3) 48Hz using two dual link tiles at 1920×2400
4) 48Hz using four single link tiles at 1920x1200

The EDIDs for all the possible connections would be interesting. I wonder if the EDIDs contain tile info like the 5K2K UltraWide display, LG UltraFine 5K and iMac 5K, and XDR 6K and old MST 4K displays. I don't think macOS supports arbitrary tiled displays (it can't do tiled 4K 144Hz or 8K 60Hz) but it might be interesting to try. If the EDIDs are missing tiled info, then maybe EDID overrides can add the info. Most tiled displays (that Apple supports) have a corresponding .mtdd file in the macOS overrides folder.

Still present with the UltraFine.

I'll do some more testing later and report back.

I guess it might be interesting to see what SwitchResX sees for the EDID.

Here's two example EDIDs direct from the display using output from AGDCDiagnose (AGDCDiagnose does not exist before High Sierra and might not get EDID info for some older GPUs):

# LG UltraFine 4K
vendor:7789 (GSM) product:23312
override product name:DisplayVendorID-1e6d/DisplayProductID-5b10

1)
override date name:DisplayVendorID-1e6d/DisplayYearManufacture-2016-DisplayWeekManufacture-12
theedid=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

2)
override date name:DisplayVendorID-1e6d/DisplayYearManufacture-2017-DisplayWeekManufacture-5
theedid=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

The only versions of macOS that have an override for the 21.5" LG UltraFine 4K are these: Big Sur, Catalina, Mojave, HighSierra, Sierra
And they all have the same override which doesn't change the EDID:

{
  "DisplayHasHardwareBrightnessSmoothing" => 1
  "DisplayPort" => {
    "PowerValue" => 5
  }
  "DisplayProductID" => 23312
  "DisplayVendorID" => 7789
}

 

[Amethyst1]

3840x2400 is a 16:10 aspect ratio - I've never thought about a 4K sized 16:10 display...

The current Dell XPS 13 laptop can also be configured with a 13.4" 3840×2400 display.

Apple has 16:10 displays using lower resolutions - old Apple displays and old and new Apple laptop displays (1280x800, 1440x900, 1920x1200, 2560x1600, 2880x1800).

There's also 1680×1050 (last 17" PowerBook; early 17" MacBook Pro; 2010~2012 15" MacBook Pro), 2304x1440 (12" MacBook) and 3072×1920 (16" MacBook Pro).

Does Apple support 13 Hz in newer macOS versions?

I just checked in High Sierra 10.13.6, on the 2010 MacBook Air (GeForce 320M), using an active Delock 62603 Mini-Displayport to DVI adapter: yes. The T221's OSD confirms it's driven as a single 3840×2400 13 Hz tile.

Do you have the DG1, DG3, or DG5 model?

I have both a DG3 and a DGP. The DGP is identical to the DG5. There's also a DGM, which is another DG5 variant for the Japanese market.

Wikipedia says it can use single, double, and quad-link for 13, 25, 41Hz (or 17.1, 33.72, and 41Hz with reduced blanking periods).

The DG3 does actually accept a pixel clock of 172.56 MHz (tested using the Delock 62603), allowing 17.8 Hz via single-link (with CVT-RB; it doesn't like CVT-RB v2). I've yet to test dual-link at that pixel clock, or see if the DGP is even more tolerant.

Can macOS see the display as more than one connection using multiple DVI inputs?

Definitely. This was on a 2008 white plastic MacBook with a Radeon HD 6870 as an eGPU, using the older DG3.

That thread documents all my eGPU experiments on really old Macs BTW. Still have some things to try when time allows.

The DG5 can do:
1) 24 - 25Hz with one dual link tile
2) 48Hz using one dual link tile of 2624×2400 and a single link tile of 1216×2400
3) 48Hz using two dual link tiles at 1920×2400
4) 48Hz using four single link tiles at 1920x1200

The DG5/DGP/DGM can also do three 1280×2400 single-link tiles at 46.7 Hz. This is undocumented and does not work on the earlier DG3, which displays heavy distortion in that configuration.

The EDIDs for all the possible connections would be interesting.

I'll see what I can do. But I think the EDIDs are the same no matter how many tiles are used. However - the T221 has several pre-programmed EDIDs that can be selected. See the manual, pages 23, 26 and 34, for that.

 

[joevt]

But I think the EDIDs are the same no matter how many tiles are used. However - the T221 has several pre-programmed EDIDs that can be selected. See the manual, pages 23, 26 and 34, for that.

What I would do is: connect the display to a Mac running a modern macOS (High Sierra or later - but not Big Sur - I don't trust it) using a modern AMD eGPU (at least Polaris?) with a DVI port. If the GPU has a DisplayPort that supports Dual Mode, then a passive DisplayPort to HDMI/DVI adapter can be used. An active adapter may alter the EDID but you can use that as a last resort or to compare with other connection types (maybe it doesn't alter the EDID).

Select each EDID, then run the following command with a different name for each GPU/output port/input port/EDID combination:
/System/Library/Extensions/AppleGraphicsControl.kext/Contents/MacOS/AGDCDiagnose -a > "AGDCDiagnose_gpu#_outputs#_inputs#_edid#.txt" 2>&1
Repeat for single, double, triple, and quad inputs (or just one of those - I guess quad would be most interesting).

Then you can load the commands from my EDIDUtil.sh script https://gist.github.com/joevt/32e5efffe3459958759fb702579b9529
source EDIDUtil.sh

Then use the commands to extract and compare all the EDIDs (install edid-decode before using decodeall). For each unique EDID, it will list the sources that included that EDID.

loadagdcfile AGDCDiagnose_*.txt
listedids > listofedids.txt
dumpedidall
decodeall

I would be interested in the AGDCDiagnose_*.txt files or the listofedids.txt file.

Anyway, if you want to try a .mtdd, then we can discuss it in a private message and report the results here. It might fail like my 4K 144Hz and 8K 60Hz attempts, or it might work.
If the EDIDs don't contain tile info, then EDID overrides would be needed (the tile info describes the relative positions of the tiles for each EDID)
A macOS EDID override can't work if all the ports of the display have the same product ID. In Windows, EDID overrides are per display vendor&product and GPU port but I don't think macOS can do that unless the graphics driver is patched (macOS EDID overrides are per display vendor&product or per display vendor&manufacture date, not GPU port).

One option is to use an external programmable EDID inserter
https://connectpro.com/product/dvi-edid/?v=7516fd43adaa
https://hackaday.io/project/18634-edid-inserter
https://lightware.com/products/edid-manager-v4
You would need an EDID inserter for each connection which would be expensive and bulky so I would use the graphics driver patch method - probably using Lilu + Whatavergreen with some custom code so that your macOS files aren't modified.

 

[Amethyst1]

I'll do some more testing later and report back.

Late 2009 27" iMac (ATI Radeon HD 4850)

- Snow Leopard (10.6.8): Monitor is detected; several resolutions up to 3840×2160 30 Hz are selectable; however, UltraFine is black regardless of mode
- Lion (10.7.5): Monitor is detected; several resolutions up to 3840×2160 30 Hz are selectable; however, UltraFine is black regardless of mode
- Mavericks (10.9.5): driven at 640×480 60 Hz; only 640×480 and 1920×1440 are selectable
- Yosemite (10.10.5): driven at 640×480 60 Hz; only 640×480 and 1920×1440 are selectable
- El Capitan (10.11.6): driven at 3840×2160 30 Hz; comes up in 1920×1080 HiDPI

Late 2010 11" MBA (NVIDIA GeForce 320M) [continued]

- Snow Leopard (10.6.8): driven at 640×480 60 Hz; no other modes selectable
- Lion (10.7.5): driven at 640×480 60 Hz; SwitchResX additionally lists 1920×1440 as "not active"
- Mountain Lion (10.8.5): driven at 640×480 60 Hz; only 640×480 and 1920×1440 are selectable
- Mavericks (10.9.5): Monitor is detected; OS says it's being driven at 4096×2304 30 Hz, however, UltraFine is black and GUI is extremely sluggish on the internal LCD
- Yosemite (10.10.5): driven at 4096×2304 30 Hz; comes up in 2048×1152 HiDPI
- Sierra (10.12.6): driven at 4096×2304 30 Hz; comes up in 2048×1152 HiDPI; brightness slider appears and is working
- High Sierra (10.13.6): driven at 4096×2304 30 Hz; comes up in 2048×1152 HiDPI; brightness slider appears and is working

Early 2011 13" MBP (Intel HD 3000) [continued]

- Yosemite (10.10.5): driven at 640×480 60 Hz; no other modes selectable
- El Capitan (10.11.6): driven at 3840×2160 30 Hz; comes up in 1920×1080 HiDPI
- Sierra (10.12.6): driven at 3840×2160 30 Hz; comes up in 1920×1080 HiDPI; brightness slider appears and is working

@joevt - Attached is the EDID of my IBM T221 DGP as read by SwitchResX via single-link.

 

[Amethyst1]

More testing with the 21.5" LG UltraFine 4K and Wacom Link Plus, this time with a 29W Apple USB-C charger connected to the latter's USB-C power input.

Late 2013 15" MacBook Pro Retina (Intel Iris Pro [5200])

- Mavericks (10.9.5): driven at 3840×2160 60 Hz (confirmed by SwitchResX: my former report of 4096×2304 48 Hz was incorrect); comes up in 3840×2160 HiDPI
- Yosemite (10.10.5): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 3840×2160 HiDPI
- El Capitan (10.11.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920×1080 HiDPI
- Sierra (10.12.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920x1080 HiDPI; brightness slider present and working
- High Sierra (10.13.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920x1080 HiDPI; brightness slider present and working

Late 2015 21.5" iMac Retina 4K (Intel Iris Pro 6200)

- Mojave (10.14.6): driven at 4096×2304 48 Hz (confirmed by SwitchResX); comes up in 2048×1152 HiDPI; brightness slider present and working

Thus, it seems resolutions with a width of 4096 pixels aren't possible on Intel Sandy Bridge (cf. post #290) or Haswell integrated graphics in macOS, at least using DisplayPort (I didn't test the 2013 rMBP's HDMI port, which is said to support 4096×2160 at 24 Hz, due to reported issues with the Wacom Link Plus when using HDMI). Broadwell does 4096×2304 just fine via DisplayPort.

 

[joevt]

More testing with the 21.5" LG UltraFine 4K and Wacom Link Plus, this time with a 29W Apple USB-C charger connected to the latter's USB-C power input.

Late 2013 15" MacBook Pro Retina (Intel Iris Pro [5200])

- Mavericks (10.9.5): driven at 3840×2160 60 Hz (confirmed by SwitchResX: my former report of 4096×2304 48 Hz was incorrect); comes up in 3840×2160 HiDPI
- Yosemite (10.10.5): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 3840×2160 HiDPI
- El Capitan (10.11.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920×1080 HiDPI
- Sierra (10.12.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920x1080 HiDPI; brightness slider present and working
- High Sierra (10.13.6): driven at 3840×2160 60 Hz (confirmed by SwitchResX); comes up in 1920x1080 HiDPI; brightness slider present and working

Late 2015 21.5" iMac Retina 4K (Intel Iris Pro 6200)

- Mojave (10.14.6): driven at 4096×2304 48 Hz (confirmed by SwitchResX); comes up in 2048×1152 HiDPI; brightness slider present and working

Thus, it seems resolutions with a width of 4096 pixels aren't possible on Intel Sandy Bridge (cf. post #290) or Haswell integrated graphics in macOS, at least using DisplayPort (I didn't test the 2013 rMBP's HDMI port, which is said to support 4096×2160 at 24 Hz, due to reported issues with the Wacom Link Plus when using HDMI). Broadwell does 4096×2304 just fine via DisplayPort.

4096 = 1,0000,0000,0000 binary
It may be that the iGPU doesn't like width that requires more than 12 bits. Double check that with Windows or Linux.
In that case, you may try custom timing of 4094x2304.

The Wacom Link Plus only supports HDMI 1.4 input which should be good enough for 4096x2160@24 Hz. I did some tests using the HDMI 2.0 port of a Mac mini 2018 and the Wacom Link Plus:
(x=fail, √=success)
x 3840x2160 24Hz 297MHz
x 3840x2160 25Hz 297MHz
√ 3840x2160 30Hz 253MHz
√ 3840x2160 31Hz 272MHz
x 3840x2160 30Hz 297MHz
x 3840x2160 38Hz 334MHz
x 3840x2160 44Hz 403MHz

x 4096x2160 36Hz 336MHz
√ 4096x2160 28Hz 270MHz

√ 4096x2304 27Hz 268MHz

297MHz are HDMI timings. My display's DisplayPort input can accept the 297MHz resolutions from the Mac's USB-C ports. My display's HDMI port can accept the 297MHz resolutions from the Mac's HDMI port (and 594MHz for normal HDMI 2.0 4K60Hz and 4096x2304@59Hz). Therefore the problem is with the Wacom Link Plus - it doesn't like 297MHz? It seems to like 272MHz or less. I didn't try to find the max pixel clock between 272MHz and 297MHz.

As for HDMI 2.0 to USB-C, the CAC-1332 (or similar) is the way to go until a better adapter that can do HDMI 2.1, DisplayPort 1.4, and 5K exists (current adapters can't do more than 4096 width).
https://www.club-3d.com/en/detail/2517/hdmi_to_usb_c_4k60hz_active_adapter_m-f/
https://insights.club-3d.com/thread/hdmi-2-1-to-usb-c-displayport-1-4-alt-mode/

 

[Amethyst1]

4096 = 1,0000,0000,0000 binary
It may be that the iGPU doesn't like width that requires more than 12 bits. Double check that with Windows or Linux.

If that's the case, I'm very surprised it only affects DisplayPort but not HDMI (at least according to specifications). Will do some more testing. I'll also give that pixel clock patch a try. I've got nothing to lose.

 

[Amethyst1]

2007 MacBook Pro + NVIDIA GeForce GTX 660 Ti (as eGPU) + 21.5" LG UltraFine 4K

- Mountain Lion (10.8.5): driven at 640×480, no other resolutions available
- Mavericks (10.9.5): driven at 4096×2304 48 Hz (confirmed by SwitchResX); comes up in 2048×1152 HiDPI
- El Capitan (10.11.6): driven at 4096×2304 48 Hz (confirmed by SwitchResX); comes up in 2048×1152 HiDPI

 

[Riviera122]

As for HDMI 2.0 to USB-C, the CAC-1332 (or similar) is the way to go until a better adapter that can do HDMI 2.1, DisplayPort 1.4, and 5K exists (current adapters can't do more than 4096 width).
https://www.club-3d.com/en/detail/2517/hdmi_to_usb_c_4k60hz_active_adapter_m-f/
https://insights.club-3d.com/thread/hdmi-2-1-to-usb-c-displayport-1-4-alt-mode/

Is this similar internally to the SIIG adapter? Haven't had too much success with that on some legacy Mac hardware (e.g. 2013 MBA only outputting at 720p). I've got a latest gen 24" 4K.

 

[joevt]

Is this similar internally to the SIIG adapter? Haven't had too much success with that on some legacy Mac hardware (e.g. 2013 MBA only outputting at 720p). I've got a latest gen 24" 4K.

They probably use the same Lontium LT6711 HDMI 2.0 to DisplayPort/USB-C chip.

 

[Amethyst1]

Haven't had too much success with that on some legacy Mac hardware (e.g. 2013 MBA only outputting at 720p).

Looks like the 2013 MBA's HD 5000 has issues outputting 3840×2160 on macOS in general. See e.g.:

4k Seiki 39" TV display corruption flashing on bottom half of screen

I've been able to get my 2013 MBA (i5/HD5000/128/8GB) hooked up to the Seiki 39" 4k TV and the signal accepted at 4k (14hz, which is fine as this is just for coding work), I get corruption on the bottom half of the screen flashing on and off at 3840x2160@14hz. Any ideas to resolve? I have...

forums.macrumors.com

Also, why are you using a HDMI to USB-C adapter when the MBA only has DisplayPort?

 

[Riviera122]

Looks like the 2013 MBA's HD 5000 has issues outputting 3840×2160 on macOS in general. See e.g.:

4k Seiki 39" TV display corruption flashing on bottom half of screen

I've been able to get my 2013 MBA (i5/HD5000/128/8GB) hooked up to the Seiki 39" 4k TV and the signal accepted at 4k (14hz, which is fine as this is just for coding work), I get corruption on the bottom half of the screen flashing on and off at 3840x2160@14hz. Any ideas to resolve? I have...

forums.macrumors.com

Also, why are you using a HDMI to USB-C adapter when the MBA only has DisplayPort?

Thanks. Just testing out my SIIG adapter with the different devices I have around. The MBA configuration was DisplayPort to HDMI adapter > SIIG adapter > UltraFine.

 

[Amethyst1]

DisplayPort to HDMI adapter

Which one? Active or passive?

 

[Riviera122]

Which one? Active or passive?

It's a passive adapter.