Questions & Answers for LG UltraFine 4K Display

No.

The LG UltraFine 5K Display is a Thunderbolt 3 display which uses both DisplayPort connections of the computer's Thunderbolt controller. The Thunderbolt controller sends both DisplayPort signals to the Thunderbolt controller of the LG UltraFine 5K over the Thunderbolt cable. The Thunderbolt controller in the LG UltraFine 5K converts both Thunderbolt DisplayPort streams back into DisplayPort to be used by each half of the display (the left and right sides) to support 5K resolution.

That is also the reason why the LG 5K display does not have a second Thunderbolt 3 port - because it is required for one of the DisplayPort signals for one half of the display. The other DisplayPort signal comes out of a DisplayPort connection of the Thunderbolt controller of the display (think of a Thunderbolt 3 dock where you can connect one display to the second Thunderbolt 3 port of the dock, and another display to a DisplayPort output of the dock).

The Thunderbolt controller of the computer does not have a third DisplayPort connection, and since the LG 5K uses two DisplayPort connections (over Thunderbolt), an LG 4K display cannot be daisy chained to the LG 5K display.

Also, since a Thunderbolt controller only has two DisplayPort connections, if you connect a LG 5K to one side of the MacBook Pro, then a second display must be connected to the other side of the MacBook Pro (there's one Thunderbolt controller per side of the MacBook Pro). One 5K or two 4K per side of the MacBook Pro can be connected.

The USB-C ports of the LG UltraFine 5K only support USB. They do not support DisplayPort because there is no other DisplayPort signal on the Thunderbolt cable that can be used and the display has no other DisplayPort inputs.

It might be possible to use a USB to DisplayPort converter (research devices that use DisplayLink, find examples at the DisplayLink or plugable websites) but they don't perform like real displays and may have issues in macOS.

• Answered by Joseph V from Fort Langley
• 11/09/2018
• Flag as inappropriate Answer (Can you daisy chain this from the LG UltraFine 5K Display?)

You can buy 2,3, or 4 and use them in tandem. They do not daisy chain though.

The LG 4K display does not have a DisplayPort output to support daisy chaining.

The LG 4K is a USB-C display (USB-C with DisplayPort alt mode, using DisplayPort 1.2 (4 lanes), and USB 2.0).

I don't know if macOS supports DisplayPort MST (for daisy chaining displays using DisplayPort). The MacBook Pro supports DisplayPort 1.2 which can't support more than one 4K 60 Hz display anyway.

Each side of the MacBook Pro (left side and right side) can support two displays. The MacBook Pro 15 inch allows up to four 4K displays. The MacBook Pro 13 inch allows two 4K displays.

Thunderbolt 3 can support two 4K 60 Hz displays from a single port using Thunderbolt display daisy chaining, a Thunderbolt 3 to Dual DisplayPort or HDMI 2.0 adapter, or a Thunderbolt 3 dock. However, I am unaware of any Thunderbolt 3 product that has more than one USB-C port with DisplayPort alt mode (required for USB-C displays like the LG 4K).

It might be possible to use an LG 4K with DisplayPort only (no USB) by using a USB-C to DisplayPort cable, but then any functions of the display that require USB will not be usable (audio, brightness control, USB hub). Brightness control may be possible using an app that uses DDC/CI.

To get two ports supporting USB-C with DisplayPort alt mode from a single Thunderbolt 3 port (so you can use the other 3 ports for other stuff), you need the following:
1) two Sunix UPD2018 or two Delock 89582 (PCIe USB 3.1 gen 2 host controller with USB-C DisplayPort alt mode port).
2) one Thunderbolt 3 PCIe expansion box with two or more slots such as the Sonnet Echo Express SE III, or two Thunderbolt 3 PCIe expansion boxes each with one slot such as the Sonnet Echo Express SEL (Thunderbolt 3 Edition).
3) one Thunderbolt 3 to Dual DisplayPort adapter such as the one made by Sonnet (not all Thunderbolt 3 products are Mac compatible so check the manufacturer's specs).

• Answered by Joseph V from Fort Langley
• 25/02/2018
• Flag as inappropriate Answer (I have the latest MacBook Pro - Can I buy two and use them in tandem as a dual monitor set? Do the monitors daisy chain?)

I was just in the Apple Store and they now use the LG displays with the Mini and MacPro. I didnt check the adapter and port used.

• Answered by James V from Pikesville
• 17/03/2017
• Flag as inappropriate Answer (Does the LG Ultrafine 4k Display work with a Mac Mini?)

60 Hz.

You can use the LG UltraFine 4K Display with these Mac models:
4096 x 2304 @ 60Hz
MacBook (Retina, 12-inch, Early 2016)
MacBook Pro (15-inch, 2016)
MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports)
MacBook Pro (13-inch, 2016, Two Thunderbolt 3 Ports)
4096 x 2304 @ 48Hz
MacBook (Retina, 12-inch, Early 2015)
A Mac with built-in USB-C or Thunderbolt 3 (USB-C) ports is required; the display isn't compatible with Mac models that use Thunderbolt 2.

See Apple Support for Use the LG UltraFine 4K Display with your MacBook or MacBook Pro for more information.

• Answered by Jay H from Middleton
• 7/04/2017
• Flag as inappropriate Answer (Refresh rate with a 2016 12 inch MacBook)

There aren't any buttons and screen will be black until you put in your usbc cable to the right port from a new MacBook Pro only. May be a MacBook. Remembering it is usb-c protocol not thunderbolt! So no thunderbolt2 to thunderbolt3 USBc option on this either!!

• Answered by David H
• 22/12/2016
• Flag as inappropriate Answer (power button lg 4 k monitor where is it)

The UltraFine 4K Display is not a Thunderbolt display.

According to the document HT207447 "Use the LG UltraFine 4K Display with your MacBook or MacBook Pro" on Apple's support website, it will not work with Macs that use Thunderbolt 2.

Maybe it will accept a DisplayPort signal? Try using a USB-C to mini DisplayPort cable to find out.

The Apple Thunderbolt 3 to Thunderbolt 2 adapter is for Thunderbolt devices only. It does not pass DisplayPort signals.

The LG UltraFine 5K Display is a Thunderbolt display but will only work at 4K @ 60 Hz when using a Thunderbolt 2 port of the Mac Pro 2013. Read the document HT207448 "Use the LG UltraFine 5K Display with your Mac" for more information about that.

• Answered by Joseph V from Fort Langley
• 13/02/2017
• Flag as inappropriate Answer (Lg ultrafine 4K and a Mac Pro 2013 will work?)