Thunderbolt 3, USB 3.1, USB Type-C: Making Sense of Connections


Things change so quickly in the tech space that even professionals sometimes find themselves stymied by the incessant and confusing terminology surrounding certain protocols (like the ones we're going to discuss today - Thunderbolt and USB). I remember the days of 8-track tapes, but I also remember when tapes were surpassed by CDs, and CDs were surpassed by MP3s, and now how MP3s are being taken over by streaming music sources. Thinking back on those days, I was constantly barraged by new terms every day that made it difficult to slog through the buzzwords: single- and double-layer CDs, WAVs, AAC, OGG, and MP3s. I longed for the days when I recorded music to a cassette from my boombox (from AM radio stations, no less) and had to manually rewind it with a pencil stuck through the tape spool.

The same goes for Wi-Fi protocols. Yes, I remember baud modems and BBS groups and ICQ messaging. Now you kids come along with your newfangled LOLs and DDoS attacks and dual-band, tri-band rock band routers and 802.11 ac—what happened to good old-fashioned 802.11 a, b, g, and n? All relegated back to the alphabet, it seems, to be replaced by new combo terms like 802.11 ac and ax. Punk kids with your fancy Internet and your loud music.

The same thing is happening to connections. If you were using and fixing computers back in the Pentium processor days, then you may remember the pain of trying to hook up peripherals to your computer. Your mouse and keyboard needed a dedicated PS/2 connector or serial port (oddly enough, many motherboards still have this as an option). Your printer? Probably a gigantic parallel port connector that was about the size of a small flash drive these days. External hard drives? How about an old SCSI connector? And how about adding a ZIP drive with a colossal 100MB of space—that’s the equivalent of 85 floppy disks! I think you can find them on eBay, and they come with a free set of dentures.

USB took care of all of that by adding a “one ring to rule them all” mentality, with an interface (Universal Serial Bus) that was supposed to uniformly combine the speed and ease of a single interface into one connector. Unfortunately, no one told Apple, which continued to offer less popular connectors such as Firewire 400/800. USB 1 debuted in 1995 with an amazing 12 Mb/s of speed. Always concerned about backward compatibility, the USB 1.1 protocol came along, which allowed the speed to decrease to 1.5 Mb/s for slower devices. By the time USB 2.0 showed up in 2000, the speed had jumped to a whopping 480 Mb/s, and ports were backward compatible with older USB 1.1 devices—which meant your USB 1.1 device could work in a USB 2.0 port, but a USB 2.0 device would not work in a USB 1.1 port. In the same year, USB flash drives became a thing, and users were able to transfer data easily between a computer and flash drives at an appreciable rate and at a higher capacity than before.

It’s never enough. Along comes USB 3.0 (also referred to as USB 3.1 Gen 1) with superior transfer speeds of 5 Gb/s (you read that right). It’s backward compatible with USB 2.0 devices, but it will only transfer at the host computer port speed; in other words, if you use a USB 3.0 port with a USB 2.0 device, the transfer speed will only top out at 480 Mb/s. As if this weren’t as confusing as pre-calculus, we now have USB 3.1 (also referred to as USB 3.1 Gen 2), with an amazing transfer rate of 10 Gb/s, and the ability to transfer at that rate over a standard USB 3.0 cable. So if you have a USB 3.1 host port, and a USB 3.1 device, but are using a USB 3.0 cable, you’ll still see speeds of 10 Gb/s. So that’s it in a nutshell, right? Wrong. Use the chart below to get your head around USB speeds, and then we’ll talk about USB Type-C and Thunderbolt™.

Not your type?

Okay? Now we have USB Type-C. USB Type-C isn’t about the speed, it’s about the design. Before all of this, USB connectors came in different sizes: Type A, Type B, mini A, mini B, micro AB, and micro B. Sometimes, finding the right cable for your device was even more confusing than figuring out your USB speed. You also had to determine which was the correct orientation for your cable—some connected in specific configurations, and flipping a cable around in the dark or behind a cord-crowded PC was a pain. USB Type-C goes in either way, upside down or right-side up, taking the guesswork out of the plug-and-play game.

The USB Type-C connector can potentially provide up to 100 watts of power, so you can use it to power and charge cell phones, laptops, and tablets, as well. Whether or not your port or device can be powered is determined by the logo. The Power Delivery (or PD) ports are signified by a battery symbol around the logo (see below).

USB 3.0, USB 3.0 with Power Delivery, USB 3.1, and USB 3.1 with Power Delivery

Another new feature of the USB Type-C connector is its ability to send DisplayPort signals over the same cable and connector as USB signals; once a defining advantage of Thunderbolt over USB. This allows users to hook up external displays over the same simple port as their mice—nice! Unfortunately, not all computers with USB Type-C ports have to support DisplayPort over USB Type-C, so be sure to check your computer’s specs since compatibility is not guaranteed.

Bring the Thunder!

So now that we’re finished with USB types and connectors, let’s move on to Thunderbolt. Thunderbolt is a transfer technology (developed by Intel®) that provides PCI Express data and DisplayPort functionality in one cable. The chart below shows the advancements made in Thunderbolt speeds and how it compares to other protocols.

Thunderbolt also allows you to daisy-chain more than one peripheral to your existing connection. Because of the host-to-user design of USB technology, as opposed to the peer-to-peer design of Thunderbolt (and FireWire before it), USB could never connect more than one peripheral in a “chain” to your host computer —imagine using one computer, connecting an external USB hard drive to it, then trying to connect another USB hard drive to that one, and so on. USB can’t do that (unless you use a hub), but Thunderbolt can, with up to six devices. USB is also not bi-directional, which means that you can't transmit and receive data at the same time, while Thunderbolt can. Also, because Thunderbolt uses a PCIe bus, you can even add external graphics cards to Thunderbolt-equipped computers, something you can’t do over a USB bus. New USB Type-C connectors will also be directional, but that function will only be available with Thunderbolt host ports. While the original Thunderbolt and Thunderbolt 2 ports used mini-DisplayPort connectors, Thunderbolt 3 uses the USB Type-C connector for all needs. The “one cord to rule them all” is finally here.

Will Thunderbolt 3 take over all transfer protocols in technology’s near future? It certainly is appealing, with its 40 Gb/s speed and USB Type-C connectivity. It also appeals to creative professionals in audio and video recording, with its ability to transfer large files quickly for near lossless experiences. But until we see Thunderbolt 3 added as a feature to more laptops and desktops, it remains on everyone’s wish list. Hopefully, this primer on USB 3.1 vs Thunderbolt 3, with a side selection of connector types, will help you make the right decision when purchasing new equipment this season.

Have any questions, comments or concerns? I know I couldn’t include everything in this short primer, but if you have anything to add, do so in the Comments section, and we’ll get back to you as soon as we can!



Thanks for this explanation.  I have been trying to find a faster backup mechanism as I have multi GB files to backup daily. I have purchased several external drives that promise fast transfers but no luck. I added a USB 3.1 adapter but that produced no increase in speed.  What do I need for my Windows PC to get 40GB backup transfers?  Do I need a Thunderbolt adapter in a PCIe slot?


Yes, a Thunderbolt 3 connection would give you a much faster connection than a USB-C 3.1. If possible, please reach out to Computer Department via Live Chat on our website until 8PM ET or call us at 1-800-606-6969 until 7PM so can make the proper recommendations based on your current Windows PC. 

Cris, many thanks for demystifying a very complex issue.  Your article and images are excellent.

Thanks for reading and for your comments, Donald S. We're glad to have helped clarify the facts.

Hello, i have Dell Optiplex 7050 on the front it has a USB C port i'm using a uGreen 2-meter type c cable when i plug in my Samsung Note 10 + 5G Dell keeps telling me 'device can perform faster if i connect to USB 3.0' but isnt the front USB C connection USB 3.0 ? As i know my Tab S6 LTE and my Note 10 + are USB 3.0. So how do i fix this issue ? 

Hi Jinnah -

Yes.  USB-C must conform to the minimum USB 3.0 standards. Try a different cable or you may need to contact Dell on this Jinnah. 

I have an Optiplex 7050 and I'd like to connect an external graphics card to it, what would be the best route? I'm wondering if the USB C connector on the front would be interchangeable with the thunderbolt 3 port on the eGPU chassis?

If possible, please contact us directly via Live Chat until 8PM ET on our website so we can assist you further. Thank you. 

I'm thinking of buying a HP Spectre laptop which claims to have a Thunderbolt 3 port , described as"1 USB 3.1 Gen 2 Type-C™ with Thunderbolt™ 3 (40 Gb/s signaling rate".  Can I get a docking unit that would have additional USB - C ports?  Would all of the new ports have 40 GB/Sec signaling rate, or would this be divided among the ports?  And would this be effective for send/receive ,read/write?   

This product would give you an additional Thunderbolt 3 port once you've plugged your laptop into it, and the top theoretical speeds (the YMMV principle always being necessary to consider) would remain 40Gb/s:

If you are wanting to connect multiple peripherals using TB 3 we'd recommend daisy chaining them. For more on that topic (and on Thunderbolt 3 in general) please see this resource we've put together:


Hi there I am about to upgrade my Mac and my soundcard to TB3, both ports will be TB3.  I use AudioQuest carbon cables generally, would their USB C-C cable be able to reach 40GB speeds, sorry I can't fin clear answers on whether USB-C cables each TB3 speeds anywhere....

"sorry I can't find clear answers on whether USB-C cables reach TB3 speeds anywhere...."

Thanks you so much for very good and informative article. 
Near the logo of this USB assign the character "D
I am asking about the port of: USB TYPE C 3.1 Generation 1, is it possible to charge the laptop using this port with a compatible cable and a portable battery (POWER BANK)?

I have a model laptop: ASUS Zenbook UX410UF-GV136. S \ N: J7N0CV08H301308

Because I'm mobile I want to charge anywhere using a POWER BANK and a compatible USB PD cable, just the question is can the laptop be charged through this PORT, because I realized there are some types of USB ports that can not be charged through?

Many thanks to the respondents for the answer.
Yehuda Ofer Nachmias

Unfortunately, your ASUS Zenbook cannot be charged via USB power delivery.  What you can use along with the AC adapter for the Zenbook is the omnicharge Omni 20+ Portable Charger, BH # OMOP2HA004.


Hello, Thanks you for this informative article.  I have a relatively new Dell 7400 2 in 1 PC with 2 Thunderbolt 3 ports.  I have a new Lenovo Thinkvision 2nd Gen 27" monitor with a built in webcam.  I cannot make the webcam work with the Thunderbolt cable (USB C each side).  The display works and sound works, but not the webcam.  I have tried adding a USB A to USB A cable and it did not help.  The webcam and everything else works if I use an HDMI-HDMI cable plus a USB A pc port connected to the USB C (Thunderbolt) port in the back of the monitor.    The monitor has 2 USB type A, 1 USB type C, 1 HDMI and 1 Diaplay ports.  Is the problem that the Thunderbolt 3 simply cannot do it all?  That seems strange to me. On top of that, which is what I want, I cannot find a 2 cable solution that includes the Thunderbolt-Thunderbolt connection.  Thank you for your time and help.

We're sorry that you're having an issue with your webcam.  It is possible that the webcam settings may have been changed in the software you're using, which would cause it to stay off when everything else is powered on. We invite you to contact us directly via Live Chat today until 1PM ET or Sunday from 10AM - 5PM ET so we can discuss the issue in greater detail. 

This is what i have

Thunderbolt 3 (USB 3.1 Gen 2 Type-C) port with Power delivery
Supports USB 3.1 Gen 2, DisplayPort 1.2, Thunderbolt 3

on dell xps15 7590 windows 10

can i run  a  usb c to dual hdmi adapter on it? Or do i need display port alternate mode? It does not say alt mode in the spec above. Or is that something i would check in windows?  Or could i run usb c to dual DP adapter?

thank you

You can use a USB-C to Dual HDMI such as the IOGEAR USB Type-C to Dual HDMI Adapter, BH # IOGUC3CHD22. Otherwise for a Dual DisplayPort, you can use the Rocstor USB Type-C to Dual DisplayPort Adapter Cable, BH # ROY10A201A1.


I have a M1 Macbook Pro on order and am wanting to get a 32 inch Monitor to work with at home. I am down to 2 choices. The BenQ PD3200U… and the BenQ PD3220U…

Since the M1 Macbook only has 2 Thunderbolt 3 ports, should I decide on the PD3200U I would also get the Caldigit TS3 Thunderbolt 3 doc…  so I could power the Macbook and connect the monitor so as to take advantage of all the ports on the monitor as well.

With the other choice, the PD3220U, would I only need the one Thunderbolt 3 cable that goes from the monitor to the Macbook to power the computer as well have the ability to make use of the ports on the monitor?

Thank You

If you used the PD3220U, one Thunderbolt 3 cable will only cover power. You would still need another for data which you can still use along with the CalDigit TS3. Basically, your set up would be AC adapter to the Macbook, then the dock, then the monitor. 

We have the Pearstone USB 3.1 Gen 1 Type-C Male to HDMI Male Cable (3'), BH #PECHD3, which will work well for this.  USB-C is the same as a Thunderbolt 3 Connection.

Looking at external hard drives, does the added speed of thunderbolt 3 really add anything? I'm not sure the hard drive itself can go that fast.

I have dell latitude 7400 notebook with thunderbol 3 port, and i have too 4k monitor dell u2720q with usb c 3.1 gen2

Can i use thunderbolt 3 cable for tranfer image and power?


i received with monitor a usb c cable gen 2A 5A, but , i don't like this cable



I have a Toshiba thunderbolt 3 dock (PA5281E-1PRP) that connects to my Toshiba laptop with a thunderbolt 3 port.  I have 2 monitors hooked up to it through this hub via hdmi cables.  

my question is, can I connect the dock to a different laptop with a USB 3.1 Gen 1 Type-C port and have it display on both monitors.  Do I need a thunderbolt 3 port on the laptop in order to display on on both monitors.

Looking at the spec sheet of your Toshiba Dynadock, one of the system requirements is "A Toshiba/dynabook computer with a Thunderbolt™ 3/USB Type-C™ port" so it may not work with other computers at all.

Thanks, yeah I saw that.  What’s throwing me off is the “/“ back slash, I think that usually mean “or”   Would hate to get a new laptop without a thunderbolt port and found out I can’t use the dock.  

Can the Macbook Pro Thunderbolt 3 power an external monitor? Everything out there talks about using the monitor to charge the macbook, but not the other way around, i.e. use the mac (connected to AC) to power the external monitor (monitor not connected to AC). 

Unfortunately, the external monitor would still need to be connected to an AC outlet when using it with a Thunderbolt 3 connection. 

Hi...I'm thinking of purchasing a new 27"-inch iMac. It has 2 USB ports (are they 3.1 and also carry Thunderbolt, no?  I plan to buy 2 LaCie d2 hard drives to go with them (transferring video and photographs, mostly) Second will back up the first.. this replaces my old late 2011 iMac which I use with the old-style d2 LaCies -- i.e. the old Thunderbolt 2 technologies (squarish ports). My question: Should I buy the cheaper Lacie  d2 Pro or the more expensive  d2  Thunderbolt 3.  The  later (more expensive) has two usb-c shaped Thunderbolt connections on back and one usb 3.1 (c-shaped, too) . The Pro  just has one usb 3.1. The more expensive d2 Thunderbolt one can daisy-chain  and add monitors (I don't need this). Does this suggest that, despite the Mac having thunderbolt port/connection, it won't connect with the Pro at Thunderbolt speeds?  And why would the d2 Lacie Pro nconnect at  thunderbolt speeds if coming from a host --the iMac--which includes? . This is confusing me...can you explain?. Need to buy something before my old drives fail. :-)

The LaCie drive with the Thunderbolt 3 ports would offer faster transfer speeds and as you've mentioned, daisy chain.  Unless you're moving hundreds of gigabytes of data each time, you wouldn't really need Thunderbolt 3 in my opinion.  USB 3.1 is plenty fast for most people. The LaCie Pro would connect to the iMac just fine via USB-C.  You would just experience USB 3.1 speeds instead of Thunderbolt 3 speeds.  

Thank you for a very informative page. I am trying to connect a Thinkpad L13 i5 laptop via a USB C (with Display functionality) to an iMac mid-2011 model via a Thunderbolt port which I presume is a "Thunderbolt 1 version", to use as a secondary monitor for the laptop. What cable or / and adapters would you suggest I use for this purpose. I looked at many products  but everyone seem have an issue somehow. Many thanks

Can I use a USB-C cable in a Thunderbolt 3 port and get that to work? Or vice versa? I know it fits, but will the connection work?


Yes to both.  Using a USB-C cable to a Thunderbolt 3 port would work but your speed would just be limited to whichever USB protocol of that cable.  So if you are using a USB-C 3.0 cable,  your max speed is 5/Gbs.

You can also use a Thunderbolt 3 cable with a USB-C port (non Thunderbolt) and speed would just be limited to the USB protocol of the port.

I have a MacBook Pro 15", Mid 2015 (MacBookPro11,4) with Thunderbolt 2 ports. Two questions:

1. Is the Apple Thunderbolt 3-to-2 adapter (…) bi-directional? Can I connect a Thunderbolt 3 device (e.g. external hard drive) to my MacBook's Thunderbolt 2 port following this connection scheme:

Thunderbolt 3 external hard drive (Thunderbolt 3 female) <—[Thunderbolt 3 male]— Thunderbolt 3-to-2 adapter (Thunderbolt 2 female) <—[Thunderbolt 2 male]— Thunderbolt 2 cable —[Thunderbolt 2 male]—> (Thunderbolt 2 female) 15" MacBook Pro

2. Following this connection scheme, can I connect a USB 3.1 Gen 2 (Type-C) device (in place of the Thunderbolt 3 device)?
For example:

USB 3.1 Gen 2 (Type-C) external hard drive (USB-C female) <—[Thunderbolt 3 male]— Thunderbolt 3-to-2 adapter (Thunderbolt 2 female) <—[Thunderbolt 2 male]— Thunderbolt 2 cable —[Thunderbolt 2 male]—> (Thunderbolt 2 female) 15" MacBook Pro

Thanks in advance!


Yes, the Apple APMMEL2AMA would allow you to do that but only with hard drives that have their own power supply, it does not have power pass through so mobile bus powered drives are not supported. It would not support USB Type C devices, only Thunderbolt.

I have an imac mid 2011 with a thunderbolt 1 port. What would be the best connector/usb hub combo to allow for the fastest transfer speeds?

On the iMac Mid 2011, you would want to use Thunderbolt for the fastest possible transfer speeds. Since you only have Thunderbolt 1, you will need to use an adapter and a cable to be able to connect a Thunderbolt 3 device.

You will need this adapter along with this cable:

Apple Thunderbolt 3 Male to Thunderbolt 2 Female Adapter, B&H #APMMEL2AMA

Apple Thunderbolt Cable (6.6'), B&H # APTBC2M

Hi, my device (SURFACE BOOK 2) and it does not support THUNDERBOLT 3, and I am trying to connect to my computer external SAMSUNG X5, whether it is possible to connect it through an adapter or any other product, I would love to receive a recommendation.

Unfortunately the drive requires a Thunderbolt 3 connection and will not work with an adapter.

Thanks for your informative article. I have a couple of questions.

A. DELL XPS provides 2 USB 3.1 Type A ports with "PowerSharing" and and Thunderbolt Type C port with "PowerDelivery". What is the difference between PowerSharing and PowerDelivery?

B. Can I safely connect and operate a powered USB 3.0 Hub to a Thunderbolt 3 Type C port on my DELL XPS laptop:

1) will the two power sources to the Hub (the HUB's external power supply and the Type C port's Power Delivery) not be in electrical conflict?

2) does the 3.0 Hub itself limit transfer speed to 5 GB/sec?


thanks in advance......paul

A. USB PowerShare in this instance refers to the ability of a laptop to use select USB ports for charging connected devices even when the laptop is powered off. Power Delivery on the other hand is a newer standard that allows for more powerful USB charging up to 100W (aka faster) and bidirectional power support (theoretically can support both receiving power and delivering power from the same port). There are a few more benefits to Power Delivery, but that is the basic understanding.

B. You can safely connect powered USB hubs to a Thunderbolt port.

1. They will not be in electrical conflict as Power Delivery requires support on both devices to fully function. In this case, there will be a USB connection between the laptop and hub and the power supply for the hub will function as normal.

2. If it is a USB 3.0 hub, then yes, you will be limited to the USB 3.0 speeds of the hub.

Shawn - I appreciate your clear and prompt reply - thanks.....paul

Sorry, Im still a little confused. 

So which is better, USB C 3.1 Gen 2 with power delivery/DisplayPort or Thunderbolt 3 USB-C with Power Delivery. 

And can I do video with ThunderBolt 3 USB C? 

Thunderbolt is the better, correct? 

Thank you.



Thunderbolt 3 is better because it includes USB-C 3.1 Gen 2 (10Gb/s) and also supports 40Gb/s transfer with Thunderbolt 3 devices. You can do video with Thunderbolt.

Hi my question is I have a Presonus 24.4.2 sound board that has firewire 400. I also have a Presonus rml32ai rackmount stage box that is firewire 800. Best solution to hook these to a laptop with usb-c or thunderbolt3. Thanks

Show older comments