Questions & Answers for Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter

The Thunderbolt 3 to Thunderbolt 2 adapter is only for connecting Thunderbolt 2 devices to Thunderbolt 3 computers, or for connecting Thunderbolt 3 devices to Thunderbolt 2 computers.

The LG 38UC99-W is not a Thunderbolt display.

The simplest way to connect the LG 38UC99-W to the MacBook Pro Retina 2015 is with a Mini DisplayPort to DisplayPort cable (not included). Connect the included USB Type A to C cable for USB functionality (to enable the two downstream USB 3.0 ports of the display).

Another option is to connect the display (with the included USB Type C cable) to one of the Thunderbolt 3 ports of a Thunderbolt 3 device that has two Thunderbolt 3 ports (such as a Thunderbolt 3 dock). Connect the Thunderbolt 3 device to the MacBook Pro Retina 2015 with the Apple Thunderbolt 3 to Thunderbolt 2 Adapter and a Thunderbolt 2 cable. This method is much more expensive, but gives you all the ports of the Thunderbolt 3 dock, and frees up the DisplayPort input of the display to be used with a different computer.

• Answered by Joseph V from Fort Langley
• 10/04/2019
• Flag as inappropriate Answer (Does this adapter + Thunderbolt Cable support connection to LG 38UC99-W USB-C port from MacBook Pro Retina 2015)

If you mean the CJ79, then I think so.

Thunderbolt 2 supports DisplayPort 1.2. Thunderbolt 3 supports two DisplayPort signals but I think only one is used for 3440x1440@100Hz (30bit color) = 14.9 Gbps so Thunderbolt 2 should be sufficient and there should be remaining bandwidth available for the USB 2.0 ports.

Only the Apple Thunderbolt 3 to Thunderbolt 2 adapter allows connecting Thunderbolt 3 devices to Thunderbolt 2 computers so this is the adapter you need.

• Answered by Joseph V from Fort Langley
• 17/02/2019
• Flag as inappropriate Answer (mac pro to thunderbolt 3 display)

The Sabrent EC-NVME is a USB 3.1 gen 2 device so the max speed you could expect is a little over 900 MB/s which is a good portion of the theoretical limit of USB 3.1 gen 2 (9.7 Gbps considering the encoding overhead of 128b/132b but not the overhead of the USB protocol).

The best (only?) way to add USB 3.1 gen 2 to a Mac that only has Thunderbolt 2 is to connect a Thunderbolt 3 device that has two Thunderbolt 3 ports using an Apple Thunderbolt 3 to Thunderbolt 2 adapter. The second Thunderbolt 3 port of the Thunderbolt 3 device can be used for USB 3.1 gen 2 devices.

Some Thunderbolt 3 docks also have other USB 3.1 gen 2 USB-C ports. If they are based on the ASMedia ASM1142 (8 Gbps PCIe 2.0x2 or 7.9 Gbps PCIe 3.0x1), then you'll get slightly better performance using a Thunderbolt 3 port. I think they all use the ASM1142 because it only requires one PCIe 3.0 lane from the Thunderbolt 3 controller leaving three lanes for other controllers (usually two USB 3.0 controllers and one Ethernet controller but sometimes a FireWire or eSATA controller).

Check the Wire Cutter review "The Best Thunderbolt 3 Docks" for more info.

• Answered by Joseph V from Fort Langley
• 18/02/2019
• Flag as inappropriate Answer (how to connect Sabrent EC-NVME (with USB 3.1 Gen 2 USB Type-C) to Mac Pro (2016) (Model: MacPro6,1 6-Core Intel Xeon E5 3.5 GHz) thru THUNDERBOLT 2?)

No, because the iPad Pro 2018 does not have a Thunderbolt controller, just like the MacBook.

It may be possible to connect the USB-C of the iPad Pro to the DisplayPort input of a Thunderbolt 3 add-in card. Then connect a Thunderbolt display to the Thunderbolt 3 add-in card. This won't allow 5K on the LG UltraFine 5K display because the LG UltraFine 5K display requires two DisplayPort 1.2 signals to achieve 5K 60 Hz. Thunderbolt displays that are greater than 4K and use the new Titan Ridge Thunderbolt controller should be used with a Thunderbolt 3 add-in card that also uses the new Titan Ridge Thunderbolt controller (such as the GC-TITAN RIDGE), which can accept DisplayPort 1.4 inputs.

• Answered by Joseph V from Fort Langley
• 15/11/2018
• Flag as inappropriate Answer (Can I connect a thunderbolt display to the new iPad pro 2018?)

I have a 13-inch 2018 MacBook Pro, the Thunderbolt 3 to Thunderbolt 2 adapter allows me to connect to the thunderbolt display, and the graphics are working fine.

The USB ports also functioned without a problem.

Updated:

To get the ethernet on the display working, I had to disconnect the USB-C adapter, delete (AFAIR) the Thunderbolt Bridge from the network preferences, and then reconnect the adapter.

• Answered by Patrick M from Portland
• 16/08/2018
• Flag as inappropriate Answer (can i connect my new 2018 macbook pro to my 2012 thunderbolt display)

No (except read below). The Thunderbolt 3 to Thunderbolt 2 adapter is only for Thunderbolt devices.

The LG 27UK850 is not a Thunderbolt display. It has 3 inputs: HDMI, DisplayPort, and USB-C with DisplayPort alt mode (not Thunderbolt).

The USB-C port of the LG 27UK850 cannot be used to power the MacBook Pro 2015. It can be used to power the MacBook or a MacBook Pro 2016 or later (but only provides 60W where the MacBook Pro might consume more during heavy usage).

For video output to the display, the simplest connection to your MacBook Pro 2015 to the LG 27UK850 can be done with a Mini DisplayPort to DisplayPort cable (not included). To use the USB downstream ports of the display (for keyboard or mouse or thumb drive or whatever you like), you need to connect a USB-C to USB-A cable (not included). The downstream ports will work as USB 3.0 (5Gbps) in this configuration.

There is a way to get video over USB-C to the LG 27UK850 from the MacBook Pro 2015. Connect a Thunderbolt 3 device that has two Thunderbolt 3 ports (such as a Thunderbolt 3 dock or RAID drive) to the MacBook Pro 2015 using the Apple Thunderbolt 3 to Thunderbolt 2 adapter. The second Thunderbolt 3 port of the Thunderbolt 3 device can be used to connect a USB-C cable to the LG 27UK850 for video and USB data.

Note that if you're using USB-C for video, then the downstream USB ports of the LG 27UK850 can only work as USB 2.0 (480 Mbps). This is because a 4K 60Hz display requires all four super-speed lines of the USB-C cable for the DisplayPort signal.

• Answered by Joseph V from Fort Langley
• 23/04/2018
• Flag as inappropriate Answer (Will this adapter allow me to connect an LG 27UK850 monitor (with USB-C) to my MacBook Pro (13", Early 2015) using a Thunderbolt 2 cable?)

You did not connect this with Thunderbolt 2. You connected it with mini DisplayPort. Same connector. Different signals.

The Cintiq 27QHD touch uses DisplayPort for the display connection and USB for the peripheral connections.

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

The iMac has Thunderbolt 3 ports which can also output USB, DisplayPort, and HDMI. You need a USB-C (DisplayPort alt mode) to DisplayPort cable or USB-C to DisplayPort adapter.

• Answered by Joseph V from Fort Langley
• 10/11/2017
• Flag as inappropriate Answer (Can i connect a wacom cintiq with this adapter to a new iMac ? I used to connect my Wacom cintiq 27 hd touch, with a thunderbolt 2 to my old iMac)