Published on 20th April, 2020 by Cable Chick

Definitive Guide to USB-C Alternate Modes

Definitive Guide to USB-C Alternate Modes

Learn about USB Type-C Alt Modes like Thunderbolt 3 and DisplayPort, and what products you can find this feature on!


What Is USB-C Alt-Mode?

USB-C Alternate Modes (or Alt-Modes) are optional features that hardware manufacturers can implement into their devices to support a wider range of data protocols for direct connection to peripherals (usually displays) without needing active adapters. USB itself carries packetized data which natively supports things like file transfers and keyboard activity. This packetized data could instead be a video signal such as HDMI or DisplayPort.

If a device supports a USB Type-C Alt-Mode, it will probably offer video out from a USB-C socket.

At the time of writing, USB Type-C has five Alternate Mode Partners, three of which should be familiar to most computer users, and only two of which we've been able to find 'in the wild':

  • Thunderbolt™ 3 Alternate Mode
  • DisplayPort™ Alternate Mode
  • HDMI™ Alternate Mode
  • MHL™ Alternate Mode
  • VirtualLink™ Alternate Mode

Of these five, the top three are the most important to regular consumers, but despite its ubiquity on televisions, HDMI Alternate Mode is a specification without an implementation (as far as we can tell). Our research turned up no consumer hardware that supports HDMI Alt-Mode by name. Instead, HDMI compatibility over USB-C is generally offered via DisplayPort or Thunderbolt 3 Alt-Modes using adapters.

For computers, Intel released Alpine Ridge controllers in 2015 which were the first Thunderbolt 3 chipsets integrated into CPUs and offered DisplayPort 1.2 spec. These were followed up in 2018 by Titan Ridge, which improved performance and brought compatibility up to DisplayPort 1.4 spec. Not all motherboards or laptops support Thunderbolt 3, even if their CPU does.

For mobile phones, manufacturers originally required separate controllers to implement Alt-Mode support, and frequently didn't (except on high-end devices). Qualcomm added Alt-Mode directly into their system-on-a-chip Snapdragon 835 in 2017, greatly expanding the number of devices which could offer video out of the USB-C socket. Still, frustratingly, not all USB-C phones have Alt-Mode support.

What can USB-C Alt-Modes Do?

USB-C Alternate Mode to a USB-C Monitor may offer Video, Audio, USB and Power Delivery.

Primarily, USB-C Alternate Modes provide single-cable connection to monitors and can offer up to 4K@60Hz/HDR video & audio directly to a USB-C enabled display. This connection can additionally offer USB-C Power Delivery and USB Hub (downstream) ports at the same time to keep your laptop/phone charging and your peripherals connected. Thunderbolt can do a bit more:

Thunderbolt Alt-Mode offers power, data, display, external graphics, Ethernet and USB all at the same time through a dynamically allocated link that can handle up to 40Gbps (but only on a 50cm cable). For example, it could deliver two 4K displays, USB 3.1 and Ethernet simultaneously over a single Thunderbolt USB-C cable when using compatible devices.

USB-C Alternate Mode to a HDMI or DisplayPort Monitor offers Video and Audio only.

DisplayPort Alt-Mode offers DP v1.2, v1.4 or v2.0 connectivity (depending on the hardware) for video connections anywhere from Full HD 1080p up to 8K@60Hz* over USB-C. Audio is usually also supported as a part of the protocol for screens with built-in speakers. Additionally, DisplayPort Alt-Mode can be used with DisplayPort, HDMI, DVI or VGA adapters for extended support to other monitor types.

HDMI Alt Mode currently offers HDMI v1.4b connectivity with support for 4K, ARC, HEC, CEC, Deep Color and a few other HDMI-specific features. HDMI Alt-Mode supports these HDMI-only features where DisplayPort Alt-Mode with a HDMI adapter does not.

*Display modes beyond 4K@60 require Display Stream Compression, a feature of DisplayPort v1.4 and up, and may additionally require DP8K certified cables for some high-bandwidth modes.

What do I need to use USB-C Alt-Modes?

  • A smartphone with DisplayPort or HDMI Alt-Mode support, or
  • A Windows 10 or Mac PC/Laptop with Thunderbolt 3 Alt-Mode support
  • A compatible screen or docking station
  • USB-C Cable of good quality, or
    • USB-C to DP / HDMI / VGA / DVI dongle or adapter cable
    • USB-C Hub with Video Support

Your first challenge will be to confirm that both your source hardware and sink hardware (monitor/dock) both offer compatible Alt-Modes and inputs for the purpose you require. Sometimes it can be as easy as checking your Laptop sockets for the DP or Thunderbolt logo, but more often (especially for phones) it will require you to go through your user manual. Alt-Mode support should not be assumed of any hardware, even high-end stuff.

Despite the new USB 3.2 naming conventions, manufacturers and hardware vendors are still using the USB 3.1 names in their documentation. Here are the equivalencies again so you know what's what:

Current Name Old Name Max. Speed Socket Type
USB 3.2 Gen 2x2 - 20 Gbps Type-C Only
USB 3.2 Gen 2 USB 3.1 Gen 2 10 Gbps Type-C or Type-A
USB 3.2 Gen 1 USB 3.1 Gen 1 / USB 3.0 5 Gbps Type-C or Type-A
USB4 Future Specification 40 Gbps Type-C Only

We'll use Gen 1 names in this blog to match up with what you're likely to see in user manuals and websites today. They have the same abilities whether you see the new name or the old.

Also, you can't always expect maximum performance on all hardware, as different speeds (bandwidths) of USB-C may limit the maximum resolution available on your device - check those manuals!

Furthermore, not all USB-C ports on a device will have Alt-Mode support. A laptop with 3 USB Type-C sockets will probably only offer Alt-Mode on one of them. Identify it ahead of time so you know where to plug in your monitor, dongle or hub.

Remember that hardware manufacturers will advertise the highest performance of their USB-C Alt-Modes, but won't state how short the cables have to be to achieve those numbers. Things like 40Gbps Thunderbolt 3 and 100W Power Delivery are usually limited to 50cm cables!

Lastly, budget devices produced early-on in the commercial release of Thunderbolt 3 hardware (we're talking laptops from 2017 here) didn't always live up to their specifications, and likewise dongle adapters and cables produced around this time weren't always full-featured either. Try to stay on this side of 2018 if you can - we've had a lot of headaches with older tech simply working as advertised.

What Type of Cable Do I Need?

For Windows-based hardware:

USB Type-C Cable

When you're connecting USB-C to USB-C, all you need is a full-featured USB-C cable. Any reputable Australian retailer should be stocking only good cables - but length plays an important role, too.

  • Up to 3m for USB 3.1 Gen 1 (5Gbps)
  • Up to 2m for USB 3.1 Gen 2 (10Gbs)
  • Up to 1m for Thunderbolt 3 (20Gbps)
  • Up to 50cm for Thunderbolt 3 (40Gbps)

These cables generally have the USB SuperSpeed+ logo, or sometimes the Thunderbolt arrow icon on them. These USB Type-C cables should offer 60W (12V/5A) Power Delivery as standard, with some higher-end cables offering 100W (20V/5A).

Thunderbolt 3 40Gbps Cable

For Thunderbolt 3 (40Gbps) at lengths over 50cm, you'll need to spend a bit more for an Active cable that's certified. You'll know these cables by the Thunderbolt arrow icon and '3' printed on each end. Thunderbolt cables without the '3' are 20Gbps only. Aim for reputable brands that you can trust to ensure the best performance.

USB-C Adapter Dongle

Dongle adapters are generally produced in 15cm lengths and are intended for use with shorter video cables. We would recommend a maximum of 5m for 4K HDMI, and a maximum of 3m for DisplayPort v1.4.

Dongle adapters may also come with hub features, including one or more USB sockets for your other peripherals. You are only guaranteed USB 2.0 speeds with DisplayPort and HDMI Alt-Modes, but Thunderbolt 3 can offer USB 3.1 speeds.

USB-C Cable Adapter

There are also cable adapters which combine the function of a dongle into a full-length cable. These are generally 1 or 2m in length, but can be up to 5m for 1080p HDMI, DVI and VGA. These cables don't have any hub functions, so they take up a USB socket and don't give any back.

For Mac-based hardware:

MacBook Thunderbolt Port

Apple devices like the new MacBook support Thunderbolt 3 Alt-Mode only. Stick with full-featured USB-C cables, or go for the 40Gbps Active Thunderbolt 3 cables described above. Thunderbolt 3 is compatible with HDMI and DisplayPort monitors through dongles, but make sure the adapters state Thunderbolt 3 support as DP and HDMI Alt-Mode adapters are not always compatible.

What products offer USB-C Alternate Mode support?

We've collected a list of popular devices which support a USB Alternate Mode. This is a mix of DisplayPort and Thunderbolt 3 Alt-Mode products. Generally Laptops are offering some level of Thunderbolt 3 functionality, while tablets, smartphones and hubs support DisplayPort Alt-Mode. Always check the product specs and/or manual to know for sure what your device is capable of connecting to.

This list is not complete, but we hope to update it from time to time as more products are released.

Last Updated: April 2020

Devices with USB-C Alt-Mode:

  • Acer Aspire Switch
  • Acer Predator 15 / 17 / 17X
  • Acer Spin 7
  • Alienware 13 / 15 / 17
  • Apple Macbook / Pro 2016
  • Apple Macbook / Pro 2017
  • Apple Macbook / Pro 2018
  • Apple MacBook / Pro 2019
  • Apple MacBook Air 2018
  • Apple iPad Pro 2018
  • ASUS ROG G5 / G7 / GX /Strix
  • ASUS Transformer 3 Pro
  • Dell Latitude 12 / 13 /15
  • Dell Latitude 7280 / 7390
  • Dell XPS 12 / 13 / 15
  • Gigabyte Aorus X5 / X7
  • Gigabyte BRIX / S
  • Google Chromebook Flip C302
  • Google Chromebook Pixel
  • Google Chromebook R13
  • Google Pixelbook 2
  • HP Elite X2
  • HP EliteBook G4 / G2 / Folio
  • HP Envy 13
  • HP Omen X
  • HP Spectre X2 / 13
  • HP Zbook 15 /17 / Studio
  • HTC 10 / EVO
  • Huawei Mate 10 / 20 / 30
  • Huawei Mate 10 Pro
  • Huawei MateBook / X
  • Huawei P20 / Pro
  • Huawei P30
  • Intel NUC
  • Lenovo Legion Y720
  • Lenovo Thinkpad P 50 / 70
  • Lenovo ThinkPad 470 / 470S / 570
  • Lenovo Thinkpad X270
  • Lenovo Yoga 370 / 900 / 910 / X1
  • LG G5 / G6 / G7
  • LG Q8
  • LG V20
  • LG V30 / V30+ / V30S
  • Microsoft Lumia 950 / XL
  • Nokia 10 Max
  • OnePlus 5 / 6
  • Oppo Find X
  • Razer Blade / Stealth / Pro
  • Razer Phone / 2
  • Samsung Galaxy S10 / S10+
  • Samsung Galaxy S8 / Plus
  • Samsung Galaxy S9 / Plus
  • Samsung Note 8 / 9 / 10
  • Samsung Notebook Odyssey
  • Surface Book 2
  • Surface Go
  • Surface Laptop 3
  • Surface Pro 7
  • Surface Pro X
  • XiaoMi Air / Pro
  • ZTE Max XL / Blade Max 3

Monitors with USB-C Input:

  • Acer H277HU
  • Acer Predator CG7
  • Acer XR382CQK
  • Asus ProArt PA32UC
  • BenQ DesignVue PD3220U
  • BenQ EW3270U
  • BenQ PV3200PT
  • Dell U3818DW UltraSharp
  • HP Envy 27
  • HP Z38c
  • Lenovo L27M-28
  • LG 27MD5KA
  • LG 27UD88-W
  • LG 34UM69G-B
  • LG UltraFine 24MD4KL-B
  • MSI Prestige PS341WU
  • Samsung LC34H892
  • Samsung S27H850QFE
  • ViewSonic ColorPro VP2771


Feel free to contact us if we've missed an important feature of USB Alt-Mode, or know of a popular product that should be on our compatibility list!

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