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Thunderbolt™ 3: The Basics

Thunderbolt 3 brings Thunderbolt to USB-C at speeds of up to 40Gbps, creating one compact port that does it all – delivering the fastest and most versatile connection to any dock, display or data device. With dozens of Thunderbolt 3 laptops, devices and cables now in the market, we have compiled a list of Frequently Asked Questions (FAQs) as it relates to Thunderbolt 3 connectivity and compatibility.

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Let’s get started with a quick run down of the tech specs:

  • Thunderbolt 3 supports – Thunderbolt, USB, DisplayPort and Power Delivery on the USB-C connector
  • The Thunderbolt 3 port and cables are small and reversible
  • Up to 40Gbps Thunderbolt 3 data transfer speeds – double the speed of  Thunderbolt 2;
    • Bi-directional, dual protocol (PCI Express and DisplayPort)
    • Four lanes of PCIe Gen 3, allowing for video cards to be connected externally to laptops for additional processing power
    • Eight lanes of DisplayPort 1.2 (HBR2 and MST) – supporting two 4K displays at 60Hz or a single 5K display at 60Hz
  • USB 3.1 Gen2 data support (10 Gbps) – compatible with existing USB devices and cables
  • DisplayPort 1.2 – compatible with existing DisplayPort displays, devices and cables. Users can connect DVI, HDMI and VGA displays via adapters
  • Thunderbolt Networking – built-in 10GbE full duplex (flowing in both directions at the same time) connection between computers
  • Daisy chaining up to six devices to a single Thunderbolt 3 port
  • Bi-directional power delivery of up to 100W system charging, where supported. Without USB Power Delivery, Thunderbolt 3 will provide up to 15W to bus-powered devices. This trickle charge can maintain host charge
  • Lowest latency for PCI Express audio

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Will Thunderbolt 3 continue to use the Mini DisplayPort connector?

The performance of Thunderbolt 3 will be delivered exclusively by the USB-C connector and not the Mini DisplayPort connector like the previous versions of Thunderbolt. Learn more about USB-C features here.

Is Thunderbolt 3 backwards compatible with Thunderbolt and Thunderbolt 2?

Thunderbolt 3 is backward compatible. Solutions and products built to Thunderbolt and Thunderbolt 2 specifications will require the Thunderbolt 3 to Thunderbolt Adapter.

Is there a maximum cable length for Thunderbolt 3 technology?

Thunderbolt 3 passive cables have maximum lengths. We currently have the following passive Thunderbolt 3 copper cables:

The maximum length of the cable refers to the maximum length at which the cables perform optimal speeds while also delivering other enabled features (power or video data). In the future we will offer active cables which will provide 40Gbps of bandwidth at longer lengths.

What is the difference between active and passive Thunderbolt 3 cables?

Active Thunderbolt 3 cables support Thunderbolt at 40Gbps data transfer at lengths of up to 2m. Optical cables are targeted later, with lengths of up to 60m. Passive lower cost cables are only capable of 20Gbps data transfer at 1m or 2m lengths, but can achieve the full 40Gbps at a shorter cable length of 0.5m.

My laptop has a USB-C port, does that mean it also supports Thunderbolt 3?

Thunderbolt 3 is marked with a Thunderbolt icon (see below) which means the host or the device has passed the rigorous certification process set by Intel. Thunderbolt 3 supports the highest specification i.e. USB 3.1 Gen 2, DisplayPort 1.2, PCI Express 3.0 and Power Delivery up to 100W.

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How many displays can I run at a time over a single Thunderbolt 3 connection?

A single connection can either support one 4K display (4096 x 2160) 30-bit @ 120 Hz, one 5K display (5120 x 2880) 30-bit @ 60 Hz with up to a bandwidth of 18Gbps of data downstream and 22Gbps upstream, or two 4K displays each (4096 x 2160) 30-bit @ 60 Hz with up to a bandwidth of 8Gbps of data downstream and 22Gbps upstream.

Further Reading

Now that you know and understand the basics of Thunderbolt 3, register here to be the first to learn about new Thunderbolt 3 developments. Stay tuned for more Thunderbolt 3 & USB-C posts on The Port!

38 Comments

  1. lk9100 5 years ago

    Hi, How can I connect a thunderbolt 3 device to a thunderbolt 2 device(Late 2013 Mac Pro)?
    would
    http://www.startech.com/Cables/thunderbolt-3-cables/thunderbolt-3-usb-c-thunderbolt-adapter~TBT3TBTADAP
    work for this purpose?

    thanks

    • Susan Mutterback 5 years ago

      Hi!
      The TBT3TBTADAP only allows you to connect a Thunderbolt 1 or 2 device (such as an external hard drive enclosure) to a Thunderbolt 3 host (such as a computer). While Thunderbolt 3 is backwards compatible with Thunderbolt 1 and 2, you may not be able to use a Thunderbolt 3 device with a Thunderbolt 1 or 2 host, due to Thunderbolt 1 and 2 not having some of the features Thunderbolt 3 has. I would recommend you check with your device manufacturer to see if it is backwards compatible.
      If you need anything else, let me know!

  2. Mike 4 years ago

    I’m developing a USB3.1 (Gen1) camera that runs about 300MBps (2.4Gbps). I am trying to find a way to get 4 of these cameras sending at this speed, into a single PC. If I put a USB3.1 (Gen1) Hub onto TB3, can I run all 4 cameras at speed? Can I somehow daisy-chain the USB cameras in a TB3 fashion somehown? [This is a custom design, so I can add HW to the camera].
    I’m currently looking into a 4 port USB3.1 PCIe card that contains a xHCI controller for EACH port (dedicated 5Gbps per port). I would like to use the new Intel Skull Canyon NUC, however, that doesn’t have PCIe slots, but has a TB3 port.
    Any suggestions?
    Thanks!

    • Susan Mutterback 4 years ago

      Hi Mike,

      If you need more in-depth help, please reach out to our Support Team and they will be able to offer you assistance: https://www.startech.com/Support

  3. David 4 years ago

    Thanks Susan, you have shared useful information with us. I hope this will help us to connect thunderbolt.

  4. Leonard Yip 4 years ago

    Do the 1 meter and 2 meter thunderbolt 3 cable support 5k at 60hz?

  5. Jed 4 years ago

    Have there been any new developments on an active 40gb/s thunderbolt 3 cable with longer than 0.5m lengths? Been 8 months since this information was published.

    • Susan Mutterback 4 years ago

      Hi Jed,

      We will have more soon! Keep eye out on our New Product page and on our social media accounts for the announcement soon.

      https://www.startech.com/Product/New

      Thanks

  6. Joon Pontén 4 years ago

    I wonder if a USB 3.1 gen2 pci card would be able to connect a macpro pre-2013 to a thunderbolt 1 raid cabinet via a usb-c to minidisplayport adapter (tb3 to tb1/2 adapter)? I have googled around but cant seem to find an answer to this particular question, which would be a game-changer for the old macpro computers.

    Thunderbolt3 supports usb 3.1g2, but is the reverse also true: does usb 3.1g2 with a usb-c port support older thunderbolt protocols?

    • Susan Mutterback 4 years ago

      Hi Joon,

      Please reach out to our Technical Support team, via chat, email or phone and they will be able to help you out. They will need to know some specifics about your setup and will be able to provide more insights.
      https://www.startech.com/support/product-support

      Thanks!

  7. gerson 4 years ago

    Hello,

    If i get a PCIe thunderbolt 3 expansion card for my windows PC, can i connect my monitors to this? I would like to know this because i wanna connect my PC and laptop to the same devices by just switching 1 thunderbolt cable.

  8. jimthing 4 years ago

    OPTICAL Thunderbolt 3 cables: when?

    • david 3 years ago

      up.
      I’m also looking for optical cables :/

  9. Zack 3 years ago

    Can I do 1 4K and 5k at the same time?

  10. Wesley 2 years ago

    Why don’t TB3 docks come with a TB port(s ) for early adopters that have invested heavily in TB 1+2 devices so that they continue to use them on newer hosts? Why are we forced to get TB3 to TB2 dongle(s ) especially if our old device does not support daisy chaining since they have a single port.

    • Danielle Mayea 2 years ago

      Hi Wesley,

      We understand this can be frustrating, however by including Thunderbolt 3 ports the docks are able to connect to both Thunderbolt 3 and Thunderbolt 2 devices (with an adapter) utilizing their full bandwidth. If these ports were Thunderbolt 2 instead, then newer Thunderbolt 3 devices would require an adapter and may also suffer from decreased performance since Thunderbolt 3’s bandwidth is double Thunderbolt 2’s.

      Hope that answers your question!
      Danielle

  11. Erik Soriano 2 years ago

    Can Thunderbolt 3 power a monitor and display picture?

    • Danielle 2 years ago

      Hi Erik. Great question! Thunderbolt 3 ports should provide up to 15W of power by default, however most displays will require more power than this. There are several displays on the market that use Thunderbolt 3 as a data connection, but they aren’t necessarily powered by Thunderbolt 3.

  12. Marc Mackey 2 years ago

    Regarding MST – my monitor say MST is not supported with HBR2 when connecting my TB3 laptop to the monitor USB-C port (Dell U2719DC). I’m not able to get a full 2560×1440 resolution on the second display via MST. Will an active TB3 cable bump the link speed to HBR3?

    • Danielle 2 years ago

      Hi Marc!
      Unfortunately, these displays are not equipped with Thunderbolt 3, therefore adding an active Thunderbolt 3 cable won’t provide a full resolution of 2560×1440 on the second display. Please note that the maximum number of displays that can be daisy chained and the resolutions that can be supported would be dependent on the host computer and the bandwidth available.
      For further support on the displays, it may be best to reach out to Dell as they would be able to provide more support for this specific display and computer.

      For more support please feel free to reach out to our 24 hour chat, available Monday – Friday. https://chat.startech.com/?lang=EN

  13. Brian 9 months ago

    I have a 16″ MacBook Pro, two 32″ 4k Thunderbolt 3 displays, and a Thunderbolt 2 GRAID. Currently, I have these all daisy chained like this: MacBook – Display1 – Display2 – RAID from a single TB3 cable to my MacBook. My displays serve as a hub and deliver 85 W of power to charge the computer. It works great. Note that my RAID drive is at the end of the chain because it’s TB2 rather than TB3. I’m thinking of upgrading to a TB3 RAID drive instead. Since everything will be TB3 then, I’m wondering what the optimal configuration is. Should I just swap the drive out as-is, or should I change it so the order is MacBook – RAID – Display1 – Display 2? That may offer slightly better disk I/O speeds, but I mostly use this for backups, so that’s not a big concern. The TB3 RAID options on the market today from Lacie, G-RAID, OWC, etc. all offer only 15 W or 27 W of power delivery with the exception of the CalDigit T4, which does offer 85 W. I think the 4-bay CalDigit one is overkill, and I’ve read it has some issues with sleep/wake, noise, etc. when it’s used upstream of other devices. Thus, I’m inclined to keep the chain with the RAID at the end. That way I keep my monitors as my main hub, I know the power delivery is enough for my Mac, and all is good with the world. Please let me know if I’m missing something – if there’s an important reason to have disks be upstream of displays. Thanks!

    • Danielle 9 months ago

      Hi Brian! How the enclosure behaves in different spots of your setup may be different based on the enclosure you’re using and the chipset that it uses. If you’re looking at a specific Thunderbolt 3 enclosure, we recommend contacting the manufacturer of that enclosure to verify if it will behave differently at the beginning or end of your Thunderbolt daisy chain. We hope that helps!

  14. Travis Meck 9 months ago

    Looking at using the Rackmount 2019 MacPro using XDR Monitor- Need specific answers on maximum distance monitor can be located away from CPU and maintain 6k resolution and specs. As Apple had no idea why I would want to place it more than 6Ft away? I Attempted to explain this machine and Monitor combo is being marketed as the solution for Audio and Video creatives I know most Facilities utilize machine rooms fo rack CPU’s and Active/Optical Cable solutions for running monitors in remote editing suites… The limited inputs on this monitor keep it from being utilized in that capacity it seems?

    • Danielle 9 months ago

      Hi Travis. We understand your frustrations with this. While an optical or active cable would be the best option for a solution like this, the maximum distance and supported resolution will be dependent on the specifications of the cable you choose. It would be best to reach out to the manufacturer of the cable you decide to purchase for the details on that. While we don’t currently offer a solution for this, we will be releasing active Thunderbolt 3 cables in longer lengths later this year.
      Hopefully, you can find a solution that properly suits your needs! If you need any other guidance our technical advisory team is available at startech.com/chat 24 hours a day, 5 days a week.

  15. Alexander Asner 7 months ago

    I wonder about the maximum cable length in a daisy chain. Is the maximum cable length of 2m valid between each device, or is it limited to a total length of 2m between all devices.

    • Danielle at StarTech.com 7 months ago

      Hi Alexander! The 2m max is per connection. So, theoretically, you can do host > 2m cable > device > 2m cable > another device > etc. There should be no issues if it is Thunderbolt 3 devices end to end.

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  6. […] docks and other external devices. I purchased my current laptop in 2016 and at the time, there were two types of Thunderbolt 3 cables — active (up to 40Gbps) and passive (up to 20Gbps). The active cables were limited to a specific […]

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