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I have the Apple MacBook 12" (2016) 1,1GHz 256GB Silver and a 4K/60Hz monitor.

I have tried this hardware to connect the displays at 4k/60Hz:

  • Anker® Aluminium USB C Type C to HDMI Converter, Supports 4 K/60Hz to HDMI Converter
  • Kanaan USB-C HDMI Adapter | USB-C USB 3.1 Type-C to HDMI Adapter Converter

This works perfectly when the USB-C port is connected directly to my MacBook.

I have only 1 USB-C port on my MacBook.

When I add a Belkin USB-C hub or even try to use the USB-C port of the Apple Multi-AV adapter, both adapters don't work, they don't provide any video output.

I have these USB-hubs/adapters:

  • Apple USB-C Digital AV Multiport Adaptor
  • Belkin USB-C 4 Port Mini Port Expansion Hub

Am I missing something here? In my ideal situation I'd like to be able to connect my 4k/60hz monitor, 1440p/60hz monitor and the charging cable at the same time, but the 1440p monitor isn't that important. I'd settle with both the 4k/60hz and charging cable at the same time.

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The reason that when you plug in your (known to be good/working) USB-C to HDMI video adapters into USB-C hubs is because the USB-C hubs don't pass the video signal that originates from the MacBook Thunderbolt port.

If you need a hub for connectivity and you want to have HDMI output, you either have to get a dock or a hub that specifically passes the video signals like the Anker Premium USB-C Hub with HDMI and Power Delivery.

Apple tried to make everything simpler with having one type of port, but (IMO) they made it more confusing. A few things to keep in mind:

  • USB-C is the physical port type. USB 3.1 is the USB specification that sets the standard for how the port functions
  • Thunderbolt 3 is the actual port on your MacBook. It just happens to use USB-C.
  • Thunderbolt 3 has many functions built into one connector
    • Video (HDMI 2.0 and DisplayPort 1.2)
    • Power Delivery
    • USB (3.1 Gen 2)
    • PCIe (PCI Express 3.0)

That's just a quick summary; for full details, see Thunderbolt 3.

So, just because an adapter "says" USB-C, dosen't mean it's going to carry all those signals/protocols. USB-C is often gives the end user the perception that "if it fits, it works." Unfortunately, now you have to verify that that what you want to do is supported by the adapter.

  • Thanks, I have 1 USB-C port, but no Thunderbolt by the way. I found out after the Apple staff recommended me their €35 USB-C(Thunderbolt)<>HDMI 2 adapter that the MacBook 12" 2016 doesn't have Thunderbolt. I returned it to the store. I have the popular Apple Multi-AV USB-c adaptor with HDMI 1.4, so I can use that when battery runs out, just means 4k will run on 30hz only. – ujjain Apr 5 '17 at 17:16
  • Also it has been established that the MacBook line does not support full Thunderbolt 3, though it may support the DisplayPort 1.2 which is what enables 4K@60. Confusing! I too am on a hunt to obtain a power delivery passthru hub that supports the full DisplayPort signal (whether through a DisplayPort output port or through an HDMI 2.0 output). – Steven Lu Jun 11 '17 at 20:59
  • No where on the page you linked to nor Anker's official page does it say anything about passing the video signals though. The page you linked to specifically says 4k/30fps. Can you provide a link that shows the video signals are passed through? – gman Nov 16 '18 at 10:26
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Yep - the USB-C port on the Macbook can't support 4k at 60Hz PLUS fast data transfer so all devices like the LG 4k monitor have USB 2 data speeds. If your main issue (like mine) is to display 4k at 60Hz while charging the Macbook the only adapter I've found that says it will do that is Hyperdrive's USB-C dock with Displayport because the USB sockets are USB 2 slow speeds only. I haven't got one yet so can't vouch for it but I've done a lot of research and it's the ONLY one that I've found that allows charging while displaying 4k at 60Hz on an external display (that isn't one of the few USB-C monitors).

  • Your link is out of date but it does appear that HyperDrive makes a few products that explicitly say they support 4k at 60hz – gman Nov 16 '18 at 10:44

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