Do We Have an Expert on USB-C?

Hey folks, what started as a review of a couple of USB-C hubs has turned into an investigation of why USB-C hubs are so limited. They all seem to have the same mix of ports: USB-A, HDMI, SD card, maybe Ethernet, but never, say, DisplayPort out or DVI out.

I can’t find good information online about why this is, other than tech news articles spitballing about bandwidth limitations. But this is TidBITS and we don’t want to spitball! I know many of you are (or were) engineers who would actually understand this stuff, so if anyone has insight into the state of things, I’m all ears, and we’ll credit you in the eventual article.

OWC has three Thunderbolt 3 docs with mini DisplayPort out and Ethernet. They have 14,12 and 10 port options.

Right, but that’s Thunderbolt 3 and not USB-C. Well, it uses a USB-C connector, but it’s not USB-C. Just so we’re clear :slight_smile:

Now I’m clear… I assume this would be for earlier (Thunderbolt 2?) computers? I’m just learning about these distinctions.

DVI is not a USB-C Alternate Mode.

I’m not sure there are any computers with both Thunderbolt 2 AND USB-C ports. The MacBook has always shipped with a single USB-C port. Later Macs have shipped with Thunderbolt 3, which uses the USB-C connector, but has much more bandwidth than USB-C.

The practical difference is USB-C hubs are about $30-100 while Thunderbolt 3 hubs cost at least $200.

Thanks Josh for the clarification

Which is interesting, because DVI and HDMI video are basically the same: a simple pin adapter can convert between the two. However, I notice from that wiki entry that DisplayPort is an alternate mode, and I’ve never seen a USB-C hub with DisplayPort output.

Part of my frustration with these hubs is trying to find the much-touted “single cable docking solution” that made giving up MagSafe worthwhile. So far, I just haven’t found it, and I doubt you could without an investment of several hundred dollars (for either a newer monitor or a Thunderbolt 3 dock).

However, I’ve acquired a number of hubs and adapter cables. Here’s what I’ve discovered connecting them to my Dell monitor:

  • USB-C to HDMI: stuck at 1080p resolution
  • USB-C to HDMI to DVI: again, stuck at 1080p resolution
  • USB-C to DVI: full resolution (2560X1440 @ 60 Hz)
  • USB-C to DisplayPort: full resolution

If I had a USB-C hub with just a single USB-C output, I could connect my USB-C to DVI cable to that and have a single-cable docking solution.

I realize this is the epitome of a first-world problem, but I’m curious why there isn’t say, a single USB-C to USB-C hub on the market. Or a USB-C hub with a DisplayPort output.

I share your curiosity and frustration.

My workaround has been to simply focus on TB3 docks and ignore USB-C for my own use. Sure, TB3 docks are more expensive. But they offer what I want in terms of power delivery, data, and desired protocols all in one convenient package.

Also, I thought part of the USB-C spec says you cannot go from USB-C to USB-C, basically no port multiplication. Unlike TB3. I’d assume that’s why you can’t find a USB-C hub with extra ports to attach your dongle to.


For those looking for background on Thunderbolt and USB-C, Glenn’s article from a few years ago remains useful. Josh is looking for current details and more in-depth detail to make sense of shipping hardware.

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I look at it this way:
USB-C designates a hardware connection ala USB-A & USB-B.
Thunderbolt 3 is a protocol that uses USB-C hardware.
USB 1.1 through USB 3.1 protocols were designed around the USB-A hardware while the USB 3.2 protocol works fastest with the USB-C hardware. However you can use a dongle to connect an USB-A connector to the USB-C port albeit with the protocol dropping the speed down to the fastest protocol the peripheral can use

So if a computer has USB-C ports they will at least be USB 3.2 protocol, but on Mac, one or two USB-C ports will use the TB3 protocol.

Since TB3 is faster than USB 3.2, it is best to use a TB3 dock for video.

I don’t know what products you’re looking at, PC manufacturers have them. The Lenovo ThinkPad USB-C Dock has 2 DisplayPorts. The Dell WD15 dock has HDMI and Mini DisplayPort. Both supply up to 60W to a laptop (Dell says it can deliver more power to their laptops) and can output either 2 1080p displays or one display at up to UHD at 30fps (which is too low a frame rate but presumably a lower resolution display could have a higher frame rate). There’s also the Dell D6000 Universal Dock but that requires DisplayLink software and may still not fully work with a Mac so it’s not worth considering.

The OWC USB-C dock has a Mini DisplayPort, you can’t attach a second display. Ethernet requires a driver on Macs.

When I want to create the single-cable dream, I stick to Thunderbolt 3 docks, the CalDigit TS3 Plus is my choice for 15-inch MacBook Pros since many don’t supply more than 60W. For 13-inch MBPs there are more options, the last one I bought was the Plugable TBT3-UDV. Otherwise, I choose USB-C multi-port adapters that may or may not have power pass-through but more importantly have the combination of ports I’m looking for.

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Do you know that particular monitor can do better than 1080p over HDMI? A number of older Dell monitors, like the UltraSharp U2713HM, are limited to 1080p over HDMI.

Yeah, that’s strictly a limitation of the monitor, but I bet a lot of people are in the same boat due to the mess that is the HDMI standard.

Thanks, I wasn’t aware of those. They do indeed fit the bill, but they’re so expensive that you might as well buy a Thunderbolt 3 dock, though the OWC model is promising.

Using these at work because Thunderbolt3 on Windows PCs is a nightmare. They work with Macs and PCs with no issues. USB 3.1 however.

I’m curious. What makes TB3 so bad on Win?

Yes, there are USB-C hubs with DisplayPort outputs.

Hyper makes a few portable adaptors. CalDigit makes desktop hubs with DisplayPort.

I have a HyperDrive SLIM 8-in-1 USB-C Hub. Excellent quality. Good price.

It also has an Ethernet port, a nice touch for those offices with wires and poor wi-fi.
Poke around their other USB-C hubs, like the HyperDrive PRO 8-in-2 hub.

The Caldigit TS3Plus+ for desktops has 15 ports, Full-sized DisplayPort among them. And an 87W power supply for a mMacBook Pro! I have one. Excellent!

It occurs to me that if there is no technical reason to prevent a USB-C dock from having Displayport connections, perhaps the reason is economic. Various chips and chipsets are used to create these interfaces, maybe the cost of adding Displayport makes a USB-C dock too expensive for the market that product is aimed at. As mentioned in other comments, those that have it are as expensive as a TB3 dock. Displayport is a different animal than HDMI, so maybe harder/more expensive to integrate.

Intel implemented a TB3 device approval which is ON by default. Device approval requires admin rights. In corporate environments users do not have admin privileges so they plug a PC into a TB3 dock and they cannot approve them. Or techs take a brand new PC out of the box and attach to a Dock to nuke and pave with the OS/Apps and the dock isn’t connected after they nuke the OS. Or a tech picks up a PC and goes to their desk to attach via Dock and they cannot login because the dock isn’t approved and Ethernet doesn’t work.

Ran into all the above when new HP ultralight ultrabooks / tablets no longer include an Ethernet jack.

Apple pre-approves TB devices. Some of the HP TB3 docks are detected but not working on Macs.

So we basically said, TB3 ain’t worth it and went with the Targus docks and as a bonus they work with Macs.

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