- USB4 is an absolute game changer.
We're talking 40 gigabit per second data rates,
support for 8K displays and external GPUs-
- Ahem.
- Single-cable docking at up to 240 watt charging rates.
(Riley coughing)
- And all over the same USB Type-C connectors
and cables that you have come
to know and to... (Riley clears throat)
Yes, what?
- Actually, USB4 is more like a collection
of optional standards, okay?
It sounds like what you're talking about is USB4 Gen 3x2,
with some of those optional features implemented.
So your sponsor, Origin PC,
would probably want you to clarify that, so. (laughs)
Okay.
- Pedantic Riley is very annoying, but he's also right.
I mean, it shouldn't surprise me coming
from the same industry consortium
that brought us naming like USB 3.2 Gen2x2.
But five years after Intel's announcement
that they would open source Thunderbolt,
USB4 is finally out in force and has turned out
to be one of the most confusing standards ever
to make it onto a consumer PC.
The good news, though,
is that by the time we are finished here,
you will understand both its pros and cons,
and how it operates or doesn't
with other standards like Thunderbolt,
including real-world examples.
(upbeat music)
The simple explanation really
is that USB4 is an open version of Thunderbolt 3
based on the specifications
that Intel released back in 2017.
There is a lot to love about this move.
For one thing, it frees vendors from the shackles
of Intel's notoriously onerous certification process.
And for another, it allows non-intel CPU manufacturers,
like Apple or especially AMD,
who didn't co-develop the standard,
to support features that used to be Thunderbolt exclusive,
like 40-gigabit data rates,
daisy-chaining together multiple devices,
and PCIe tunneling, which is super cool
and allows you to turn your USB-C port
into a PCI-Express connection
for devices like external GPUs and other add-on cards.
The problem is that
when you free the notoriously cheapskate computer industry
from compliance programs, you invite shortcuts.
And USB4 invites a lot of shortcuts.
In no particular order,
here are the optional components of the spec
that can be left off of your device
while still allowing the vendor to slap USB4
on the spec sheet:
40-gigabit transfer rates,
20-gigabit USB 3.2, Thunderbolt Alternate Mode,
USB-C Alternate Mode, and yes, PCIe tunneling.
Yeah.
In a world where almost nothing you can connect
to a laptop needs the speed
of even a last-gen USB3 20-gig port,
isn't the whole point of USB4 PCIe tunneling
and interoperability with Thunderbolt 3 devices?
Well, Microsoft sure thought so,
which is why they actually require external USB4 ports
on Windows 11 devices to support PCIe tunneling,
which theoretically ensures backwards compatibility
with Thunderbolt 3 devices.
But there is no such guarantee
if you were to buy a bare motherboard
or a non-Windows device.
And from my conversations with a device maker
whose previous Thunderbolt 3 notebook
actually never ended up getting certified by Intel,
there's a lot more to this interoperability
than just checking a box for PCIe tunneling.
Making matters even more confusing,
Microsoft does not appear to have mandates in place
for any of the other features.
The good news is that when it works, it works really well.
Here is a small bushel of Thunderbolt 3,
Thunderbolt 4, and USB4 devices
that we've tried on the Voyager a1600 gaming
and content creation laptop
that Corsair provided for this video.
And I'm gonna show you guys what the experience
is like on a USB4 laptop
after this short message from our sponsor.
Corsair packed the Voyager a1600
with high-performance gear,
like their Vengeance DDR5 memory,
and yet managed to keep it amazingly slim.
The Integrated Elgato Steam Deck allows you
to map streaming commands
and keyboard shortcuts to 10 easy-access,
customizable shortcut buttons
using simple drag-and-drop customization.
And Corsair's iCUE software lets you fully customize
the system's look, monitor performance,
and manage your Corsair devices
so you can update and fine-tune the settings to your needs.
It comes with a one-year comprehensive warranty
for peace of mind,
making it the premier choice for laptop PC gaming,
or content creation, in a super compact package.
Visit the link down below to learn more.
For our first trick,
we'll be trying to connect a couple of Thunderbolt 3 devices
to our USB4 laptop.
And the reason this matters is
because these older devices would've been designed at a time
that USB4 compatibility wouldn't have been a consideration.
So if they work,
it means that USB4 is transparently compatible
with Thunderbolt 3.
At least, okay, this one works
for these particular devices.
Now, that first one I plugged in using a USB4 cable,
and the second one
we're gonna try an older Thunderbolt 3 cable.
I think we got it. There it is.
CalDigit 10-gig network adapter.
This backwards compatibility means
that any Thunderbolt 3 device
and USB4 system should work with each other.
Now, I would expect to find some edge cases,
particularly with very old devices,
due to Intel-specific handshakes that used to be required.
But we didn't run into any of them
while we were working on this video.
Now let's try a Thunderbolt 4 device.
In the interest of giving ourselves our best shot here,
we're gonna go ahead and use
a Thunderbolt-4-validated cable.
Look at that. Easy.
And we don't even need that old Intel application
for managing all of our connected devices.
I mean, I expected this to work.
The main difference between Thunderbolt 3
and Thunderbolt 4 is actually also
in enforcement of compliance.
So Thunderbolt 4 requires,
in order to get the Intel badge,
support for two 4K displays or a single 8K display.
Computers must have 32 gigabit per second of PCIe bandwidth.
This is to address issues folks would have
with high-bandwidth devices
on some Thunderbolt 3 laptops, particularly eGPUs.
And they must support security improvements
that protect your device from malicious connected devices.
Plugable.com actually has a great writeup
on the differences between Thunderbolt 3 and Thunderbolt 4.
What about speed, though?
In an attempt to crack
over 20 gigabit per second of transfers,
we are using three separate SSDs and our network share,
oh, and copying all to our boot drive at the same time.
3.6 gigabytes a second. Yes!
Can confirm that we are not limited
to 20 gigabit per second,
even though that could be the case with USB4.
Wow, those transfers are almost all done.
That's really impressive.
Those were 22-gigabyte files. Mind blowing.
And the most mind blowing thing
is that aside from some CalDigit devices
that took a little while to be detected,
we didn't run into any issues using Thunderbolt devices
on this laptop.
And those CalDigit ones,
they were actually just downloading drivers
in the background.
Wow.
But there is definitely more to know here.
We tested a lot of configurations
and discovered not only some differences
between Thunderbolt and USB4,
but also between Apple's implementation
and the one we found on the Corsair Voyager.
See, on a Mac, two similar 5K displays,
this would work.
Just connect them to any Thunderbolt port you want
and it works as expected.
However, when we attempt to do the same thing
with the Voyager, either only one display works,
or if we go through a hub,
we can run both of them,
but they're limited to 4K resolution.
Unless, da-da-da-da-da-da-da,
we actually unplug them from our Thunderbolt ports,
plug one into Thunderbolt
and one into the regular USB-C 3.2 port
over on the other side.
Et voila, both running at 5K.
The reason for this is quite interesting.
In The Verge's coverage of this laptop,
Corsair's senior public relations specialist Justin Ocbina
revealed that the USB4 ports are hooked up
to the CPU for display.
Meanwhile, the 3.2 ports are hooked up to the GPU.
So they might look the same,
but because they're running DisplayPort Alt Mode,
they're limited to the capabilities
of whichever GPU is physically attached to them.
So we're able to run more than one 5K display
by connecting to each of those GPUs separately.
This is another really interesting example
of different protocols behaving in different ways,
even if they go over the same connectors.
Now, Alt Mode, what we're talking about here,
uses a physical chip connected to the USB port
to send a signal down that differs from standard USB.
Tunneling is not the same.
It converts the DisplayPort signal to packets
that can be sent along a USB connection,
allowing for things like data and PCIe tunnel packets
to be sent alongside.
So your mileage may vary depending on
whether your machine uses Alt Mode or tunneled DisplayPort.
Poor Tanner.
If only Apple could have provided a display
with an actual stand.
Okay, you're good. You're unplugged.
Yeah, he's got the tracksuit and everything.
Okay, thank you.
Let's try some older, more obscure stuff,
like this Akideo dual-drive dock and,
ooh, how about this Thunderbolt archival tape backup system?
I remember the tape drive
actually requiring special software.
So it's possible this hard drive will show up,
even if the tape drive wouldn't.
Oh, hey, there we go. Look at that.
That's awesome.
All right, goodbye, monitor. External drive.
And there they are. That's wild.
I mean, it shouldn't surprise me that much,
given that USb4 is supposed to be
based on the Thunderbolt spec,
and therefore should be the same thing,
but you just don't expect tech
to work that well right out of the gate.
And there were some things that led me to believe
that maybe they weren't quite the same.
For example, Thunderbolt has supported
multiple Thunderbolt devices daisy-chained together
since the beginning.
But the Wikipedia page for USB4 before explicitly says
that such daisy-chaining is not supported.
To clarify, you could totally plug a Thunderbolt hub
into your USB4 laptop,
and then a USB hub into that,
and another one into that, and so on and so forth
until the signal timing becomes an issue,
but Intel seems to believe that connecting
additional PCIe tunneling devices downstream,
well, that's their jam.
So what happens if we try it?
I guess we've already got this guy right here.
So instead of plugging our additional drives
into the laptop directly, why don't we daisy-chain?
I see the hard drive in here so far. There they are.
The SSDs in here have shown up. But how far can we go?
Why don't we do a hub, right? All right.
Oh yeah. Okay.
I don't know if we have to go all the way to six,
but let's do one more at least here.
Here comes another one.
There they are. It's all showing up.
I want one more. I want my 10-gig ethernet.
6A. Oh.
Oh. (laughs)
- [David] Nope, it does not like that one.
- We got it working with anywhere
from two to three devices pretty consistently,
but as you can see, your mileage may vary.
Though this is unlikely to ever affect you.
Many newer Thunderbolt devices, especially hubs and docks,
have controllers in them that can communicate
either using Thunderbolt-like PCIe tunneling protocols
or traditional USB protocols.
So in many cases, it won't necessarily be obvious to you
until you try to plug in another downstream device
which protocol your device is using.
Now, rather than trying to run all five of these devices,
let's go for a single really demanding one:
An external GPU.
Here we go. Oh, the fan's spinning.
That's a good sign. There it is.
Our RTX 2070 external GPU.
Not that we'll need to upgrade the GPU anytime soon,
given that this laptop has a Radeon 6800
in it already anyway, but the point is that it does work.
And the a1600 does all of this partly thanks
to AMD's inclusion of USB4
on their Zen 3+ Ryzen 7000 processors.
But in the absence of Intel's standards compliance team,
it's also thanks to the way that Corsair has worked
with their OEM to internally validate their implementation.
However, watch how easily I can break things.
Whoops. Here's what happened there.
While Thunderbolt has used the same USB-C connector
as USB devices for half a decade now,
the Thunderbolt protocol,
which you've heard me refer to a few times,
and it's kind of like the language
that's actually being spoken over the cable,
well, it's closer to PCI-Express than it is to USB.
So this, along with
its traditionally much higher data rates,
means that it has far less tolerance
for latency and inconsistency,
which means that cable quality matters a lot.
It's not all bad, like here.
Oh, this anchor cable is one
that I specifically pulled aside for this.
And this is pretty cool
because this cable is older than the USB4 spec.
It's just a high-quality C-to-C cable.
And give it a second.
Oh, wait, did that not work?
I actually tried it on a different Thunderbolt-only device.
This network adapter.
And on the network adapter, it totally works,
in spite of this thing not having a USB operating mode.
That's wild.
Let's try this USB4 Type-C cable,
one that is actually a newer, validated one,
and see if the external GPU picks up that one.
No.
As you can see, standard USB-C cables might work fine,
even with Thunderbolt-only devices,
but only the ones with the built-in signal stabilizer,
like this one, are actually guaranteed
to work with Thunderbolt devices.
And that's gonna be true for any connection using
that PCIe-based Thunderbolt protocol
regardless of whether it's
on an Intel-certified Thunderbolt device or a USB4 device.
This is why USB4 is only rated at 40 gigabit per second
over a one-meter cable,
while Thunderbolt 4 is rated at that same speed
at up to two meters.
To my knowledge, there are no
non-Intel-Thunderbolt USB4 signal-stabilized cable products.
And curiously, this is another really interesting one,
this active Thunderbolt 3 cable
from Corning didn't work on any of our devices
on our USB4 laptop here.
Hold on, I can just demonstrate this real quick.
There we go. Yeah, no dice.
Which means that our days
of hit-or-miss cable compatibility are not over,
even if they are a lot better.
To answer the question, then,
is USB4 compatible with Thunderbolt 3 and 4 devices?
The answer is yes, but also no.
The level of compatibility really
is gonna come down to how good of an implementation you get.
The Corsair Voyager a1600 performed admirably,
but it's a machine that implements far better
than the bare minimum spec,
and one that doesn't go this far may not be as smooth.
And as we saw today,
your mileage may vary when it comes to unofficial features,
like daisy-chaining and support
for specialty cables like these optical ones from Corning.
The big question this raises, then, is,
why did the USB-IF allow half-baked USB4 at all?
Well, it seems to come down to phones.
Mobile devices could get some very valid benefits from USB4,
like higher data rates
and DisplayPort tunneling for external devices
with Samsung DeX or whatever,
but they're unlikely to need the PCIe tunneling
that Thunderbolt is known for,
or daisy-chaining and the like.
They're also unlikely to need this segue
to our sponsor that I'm known for
'cause we already told you it's sponsored by Corsair.
If you guys enjoyed this video
and you're looking to learn more about Thunderbolt,
this video on ShortCircuit shows off
my very favorite Thunderbolt 4 dock.
It's actually this one. It's freaking awesome.
2.5-gig LAN.