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Apple released Thunderbolt 3 to Thunderbolt 2 adapter. Is it possible to connect an external device using type C (ie ASUS MB169B+) by connecting the Thunderbolt 3 to Thunderbolt 2 adapter with an Thunderbolt cable into the Mac (this is an older Mac before 2015)?

Can the MacBook (which only supports Thunderbolt 2) fully access the device which supports type C? The transmission traffic still won't compare with the real Thunderbolt 3 speeds but at least the Thunderbolt 2 ports are not useless!

grg
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BroccoliBoy
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8 Answers8

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Let's break your question into two questions.

  1. Can I use the ASUS MB169B+ with a Thunderbolt 1/2 Mac?
  2. Is there a generic way to connect any arbitrary Thunderbolt 3 or USB Type C peripheral to a Thunderbolt 1/2 Mac?

First let me address your specific example. The ASUS MB169B+ is actually just a regular USB 3.0 device. It uses a technology called DisplayLink which basically is a video card connected over USB (instead of the typical PCIe connection.)

Because MB169B+ is a regular USB device, you can simply connect it to one of your MacBook's regular USB ports and it will work just as well as it would connected to a USB Type C port.

Now for the second question, can you use a Thunderbolt 3 (or USB Type C) peripheral with a Thunderbolt 2 computer? Theoretically, yes it is possible to create a dongle that accomplishes this. You would have to put a Falcon Ridge controller and an Alpine Ridge controller in to the same dongle and connect them together like so:

            +--------Thunderbolt 2 to 3 Adapter Box--------+
            |                +--> PCIe --+                 |
MacBook --> | Falcon Ridge --|           |--> Alpine Ridge | --> Thunderbolt 3/Type C
            |                +--> DP ----+                 |
            +----------------------------------------------+

While a dongle exactly as above does not exist, there is an interesting workaround. The Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter you mention has some limited ability here. While the Apple adapter does work as a generic 3 to 2 adapter, it can only go from 2 to 3 if the peripheral on the other side is a native Thunderbolt 3 device. For example, this adapter works for connecting a LG UltraFine 5K Display to a Thunderbolt 2 Mac. However, it won't work with the 2016 21.5" LG UltraFine 4K Display since that monitor is USB-C only and not a Thunderbolt 3 device. It will work with the 2019 23.5" LG UltraFine 4K Display since that monitor has Thunderbolt 3.

Now, here is where things start to get weird. If you buy a Thunderbolt 3 dock, for example the CalDigit TS3 Plus Dock you can use the Apple adapter to connect a Thunderbolt 2 Mac to it. Most Thunderbolt docks have two Thunderbolt ports on them, one upstream port to connect the computer to the dock and one downstream port for daisy chaining more Thunderbolt devices. That downstream port is actually a full featured USB-C port as well, with support for Thunderbolt 3, Display Port Alternate mode, and USB 3.1. So you can actually plug the 2016 21.5" LG UltraFine 4K Display in to that downstream port and it will work!

It's pretty crazy but the following connection sequence actually works:

Thunderbolt 2 Mac --> Thunderbolt 3 to 2 Adapter --> Thunderbolt 3 Dock --> 2016 21.5" LG 4K

But this sequence (un-intuitively) does NOT work:

Thunderbolt 2 Mac --> Thunderbolt 3 to 2 Adapter --> 2016 21.5" LG 4K

So in summary, the combination of the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter with a Thunderbolt 3 dock creates a fully featured (and expensive) Thunderbolt 2 to Thunderbolt 3 adapter.

nohillside
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nldesi
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    We are now mid-2018. Has anything evolved on this front? In my case, I would like to connect Macs with Thunderbolt ports to an LG UltraFine 4K Display. – Jean-François Beauchamp Jun 19 '18 at 23:17
  • I want to connect my late 2015 macbook to my z390 desktop. when I have powerful graphics desktop with thunderbolt 3, why do i need an eGPU for my macbook? – Necktwi Aug 29 '19 at 04:45
  • and you saved me from buying the marketed adapter. – Necktwi Aug 29 '19 at 05:13
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    @nateman1352 Thanks for the answer. This might be a dumb question but how do I connect a Thunderbolt 2 Mac to the Thunderbolt 3 to 2 Adapter? Don't they both have a female Thunderbolt 2 connector? – Domon Mar 17 '20 at 06:45
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    @domon you basically plug the adapter in backwards: you plug the male (TB3) end into the dock and the TB2 end then can be connected to the computer via an additional TB2 male to TB2 male cable. It works great with the aforementioned CalDigit dock and mostly well with the CalDigit USB-C Pro Dock. Alas, it doesn't work with any dock that has an integrated cable, since I haven't found a way to couple a TB3 male cable to the adapter's TB3 male end. – Timothy R. Butler Aug 07 '20 at 03:40
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    This is easily the best answer I've seen on AskDifferent, possibly SE in general. It addresses both the intent and the letter of what OP asked, both informing and giving actionable insights. – ijoseph Oct 20 '20 at 22:41
  • It's amazing any of this high speed signaling works at all. I'm sure it has periodic hiccups and picks up random noise every once in a while. Back in the day, moving a couple of megabits per second using SCSI required thick multicore cables and terminators. – ATL_DEV Dec 24 '21 at 18:33
4

All Mac with thunderbolt 2 are limited since thunderbolt 2 doesn't embed USB C. Even with the thunderbolt 2 to thunderbolt 3 adapter, you could physically connect a USB C display like the ASUS MB169B or the LG 4K Display and they won't work.

New Mac with USB C connectors will work and don't need the adapter. whether you have the MacBook "one" or the MacBook Pro that combine thunderbolt 3 and USB C in one physical port, they should connect to USB C displays.

The only case where a thunderbolt 2 Mac can drive a new connector display with the adapter is if the display supports thunderbolt explicitly as opposed to USB. The LG 5k display is one such new monitor that would work with many thunderbolt 2 Mac. This results in lower resolution, though - 3840 x 2160 @ 60Hz

bmike
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  • " The only case where a thunderbolt 2 Mac can drive a new connector display with the adapter is if the display supports thunderbolt explicitly as opposed to USB. " There are TB2 to USB 3.x adapters available, with USB-A though, Kanex makes them. Putting a USB 3.x PCIe card with USB-C ports in a TB2/PCIe case would be trivial, though expensive. Adapters to plug USB-C devices into USB-A ports exist but are dangerous, don't use them. – MacGuffin Jan 02 '21 at 06:01
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I have the following setup and it does work:

Power is not passed though. USB 2.0 is passed through (tested Epson V550 scanner with a USB 2.0 to USB-C adapter). I have not tested USB 3.0 passthrough.

Edit October 2020: I can confirm that two of these 4K UltraFine displays does work. I duplicated the setup above, except with a 2m Thunderbolt 2 cable instead of 0.5m, and it works well. It does not work if you have the displays daisychained using Thunderbolt 3. System Information output:

NVIDIA GeForce GT 750M:

Chipset Model:    NVIDIA GeForce GT 750M
  Type: GPU
  Bus:  PCIe
  PCIe Lane Width:  x8
  VRAM (Total): 2 GB
  Vendor:   NVIDIA (0x10de)
  Device ID:    0x0fe9
  Revision ID:  0x00a2
  ROM Revision: 3776
  Automatic Graphics Switching: Supported
  gMux Version: 4.0.8 [3.2.8]
  Metal:    Supported, feature set macOS GPUFamily1 v4
  Displays:
Colour LCD:
  Display Type: Built-In Retina LCD
  Resolution:   2880x1800 Retina
  Framebuffer Depth:    24-Bit Colour (ARGB8888)
  Mirror:   Off
  Online:   Yes
  Automatically Adjust Brightness:  No
  Connection Type:  Internal
LG UltraFine:
  Resolution:   6016 x 3384
  UI Looks like:    3008 x 1692 @ 60 Hz
  Framebuffer Depth:    24-Bit Colour (ARGB8888)
  Display Serial Number:    904NTJJ33476
  Main Display: Yes
  Mirror:   Off
  Online:   Yes
  Rotation: Supported
  Automatically Adjust Brightness:  No
  Connection Type:  Thunderbolt/DisplayPort
LG UltraFine:
  Resolution:   6016 x 3384
  UI Looks like:    3008 x 1692 @ 60 Hz
  Framebuffer Depth:    24-Bit Colour (ARGB8888)
  Display Serial Number:    903NTWGCD545
  Mirror:   Off
  Online:   Yes
  Rotation: Supported
  Automatically Adjust Brightness:  No
  Connection Type:  Thunderbolt/DisplayPort
mango45
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0

You can do this with a simpler and cheaper USB-C female to USB-A male adapter. For example you could buy this:

https://www.amazon.com/Lemeng-USB3-0-Connector-Converter-Adapter/dp/B01ABTHI7C

Note that this only works with USB devices, i.e. for example monitors that need the alternate-mode DisplayPort signal won't work.

jksoegaard
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  • " You can do this with a simpler and cheaper USB-C female to USB-A male adapter. " This is not simpler because a USB-A to micro-USB-B cable is already simple. It's not cheaper because adapters like that in the link violate the USB spec and can permanently damage expensive hardware. Getting the right cable is cheap, simple, and won't set USB cables on fire. USB-A to DP video cables and docks exist, DisplayLink makes the chip and a number of peripheral makers use the chip in their products. TB2 to DP cables and docks will be simpler and cheaper if there are TB2 ports on the computer. – MacGuffin Jan 02 '21 at 05:40
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See the below apple product Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter

The Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter lets you connect Thunderbolt and Thunderbolt 2 devices — such as external hard drives and Thunderbolt docks — to any of the Thunderbolt 3 (USB-C) ports on your MacBook Pro. As a bidirectional adapter, it can also connect new Thunderbolt 3 devices to a Mac with a Thunderbolt or Thunderbolt 2 port and macOS Sierra.

Anthony85361
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  • This is not necessarily true. As pointed out above the adapter does not give the older Thunderbolt 2 computer the embedded USB C protocols that it lacks. A T3 peripheral that happens to have a USB C port would theoretically work but really it would probably have an actual T3 port not a USB-C. And T3 is backwards compatible with T2 at T2 speeds/protocols. – Beartech Dec 22 '17 at 18:01
  • Also as I discovered, the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter does not pass power. I wanted to use it to connect a bus powered Thunderbolt 3 SSD drive to my older iMac until I can upgrade it. Turns out this seems to be impossible. – Robert J Berger Mar 23 '19 at 19:08
  • " Also as I discovered, the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter does not pass power. I wanted to use it to connect a bus powered Thunderbolt 3 SSD drive to my older iMac until I can upgrade it. Turns out this seems to be impossible. " Not impossible, just expensive. There are TB3 docks that with a TB2 to TB3 adapter will provide powered USB-C ports with USB 3.x and TB supported. Perhaps not a wise investment but it will allow use of USB-C bus powered TB and USB devices on TB2 hosts. – MacGuffin Jan 02 '21 at 06:34
  • Anthony85361 the TB3 to TB2 is not bidirectional , already purchased it, as @MacGuffin said it will not work because no power passed over the line. – 0xFK Jul 08 '21 at 10:31
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IN reality the older TB2 mac may lack the proper video output rendering a 2K output. If one has the Retina which support 4k then that unit has HDMI onboard or one has a Mac Pro Tower and then a high end video card is in line with a possible solution. In any case I do not believe the TB2 can push the speed necessary for 4K or greater.

user309563
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    " In any case I do not believe the TB2 can push the speed necessary for 4K or greater. " TB2 supports 20 Gbps. Uncompressed 5K@30Hz requires 11 Gbps. Bandwidth is not a problem and many Apple computers with TB2 supported 5K natively. A TB2 GPU will certainly add capability beyond what is already under the hood. – MacGuffin Jan 02 '21 at 06:17
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Well ASUS MB169B+ support page has a download for MacOS 10.15.5 or greater. So it seems it will in fact work. Since this was an old question, it might not have worked 3 years and 3 months ago.

The ASUS website doesn't like Safari try Chrome/Firefox instead: https://www.asus.com/us/Monitors/MB169BPlus/HelpDesk_Download/

Version 1.0.0 2020/07/1710.28 MBytes

MB Series USB Monitor APP for Mac OS 10.15.5 or higher This APP enables you to use ASUS MB series monitor with Mac OS system via USB 3.0 signal. If your operation system is upgraded to Mac OS 10.15.5 or higher, please upgrade and install this APP accordingly. If your operation system is still staying at version before Mac OS 10.15.5, please keep using driver 5.2.1 version When connecting with USB 3.0 mode, certain content or apps with security protection on host devices may prohibit the viewing of protected content on MB series monitor. If you have paid media content on your device, it is possible your app may limit its viewing to your host device only.

ASUS makes mention of earlier drivers but doesn't provide anything prior to Mojave on their web page. But apparently those drivers/apps were available in the past.

James Brickley
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Using the Moffie USB-C with MDP 1.5m cable, I successfully connected outputting from a Thunderbolt 2 Mini DisplayPort (iMac Late 2014) inputting to the LG Ultrafine 4K 24-inch 24MD4KL-B as an external display. The screen controls in the iMac's Settings-Display and the Mac keyboard are limited: No brightness control, can't effectively calibrate the monitor. I am fussy about monitor quality and I'm very happy with the LG as an external display for my iMac. The LG is using the native 4K resolution.

frog22man
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