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Thunderbolt 5: Only Necessary for the Most Demanding Uses

Glenn Fleishman

The first Thunderbolt 5 ports on Apple products appeared this week with
the updated Mac mini and MacBook Pro models based on Apple's new M4 Pro
and M4 Max chips. (The plain M4 models use Thunderbolt 4.) Thunderbolt
5 expands on features introduced in previous releases and won't make
much of a difference until peripherals catch up. Even then, few people
will truly need what Thunderbolt 5 offers, unlike the significant
changes made several years ago with the move from Thunderbolt 2 to
Thunderbolt 3.

Intel released the final Thunderbolt 5 specification in September 2023;
the first peripherals and cables with Thunderbolt 5 [1]appeared in
August 2024. Apple is the first to incorporate Thunderbolt 5 into a
computer.

Thunderbolt 5's enhancements revolve around faster data rates, high-end
video capabilities, and higher-wattage power delivery.

What's New in Thunderbolt 5

Thunderbolt 5 can carry up to an aggregate of 160 Gbps, splitting that
bandwidth in one of two ways. In typical usage, it will carry 80 Gbps
of symmetrical data flow to and from a peripheral. However, it also
supports a 120 Gbps/40 Gbps asymmetrical option for so-called
'video-intensive' uses, which boils down to multiple high-resolution
displays or displays with super-high refresh rates. (Refresh rates
higher than the typical 60 hertz make moving images on a display appear
more fluid and reduce blur'something desirable when watching sports,
action movies, or playing games.)

Those video capabilities come as part of Thunderbolt 5's support for
[2]DisplayPort 2.1, which can leverage up to 80 Gbps of data for
single-display refresh rates as high as 240 Hz with 4K displays,
support multiple 8K monitors at fast refresh rates, or drive a single
16K display at 60 Hz. With 120 Gbps, more displays at higher
resolutions or refresh rates can be used.

Thunderbolt 5 also adds compatibility with 240-watt cabling and
charging, meeting the USB Power Delivery (PD) 3.1 standard set in 2021.
Apple created its own 240W charging variant over MagSafe 3 for the
power-hungry 16-inch MacBook Pro, which requires 140W, because it came
out before USB and Thunderbolt provided high-wattage support. (You can
now use a Thunderbolt 5 cable to fast-charge the 16-inch MacBook Pro.
In August 2024, Apple quietly released a $29 [3]240W USB-C Charge Cable
that's $40 less than the company's $69 [4]Thunderbolt 5 Pro Cable.)

Finally, while Thunderbolt 4 supports USB4, Thunderbolt 5 supports USB4
2.0, which doubles USB4's maximum data transfer rate from 40 Gbps to 80
Gbps, provides enhanced bandwidth allocation of up to 120 Gbps over
three lanes, supports up to 240W power delivery, and offers DisplayPort
2.0 compatibility. (Yes, it's called USB4 2.0, not USB5. We're not
responsible.)
Feature Thunderbolt 3 Thunderbolt 4 Thunderbolt 5
Max data
rate 40/40 Gbps 40/40 Gbps 80/80 or 120/40 Gbps
Max power delivery Under 15W or 100W 100W in most cases 240W option
USB level USB 2, USB 3.1 or later Plus USB4 Plus USB4 2.0

That's the nut: if you don't need data rates over 40 Gbps or plan on
using super-high-refresh or super-high-resolution displays, Thunderbolt
5 won't make any difference in your life. That's why Apple supports it
only on the M4 Pro and M4 Max machines targeted at high-end
professionals rather than the whole M4 lineup. Arguably, most of
Thunderbolt 5's features are aimed at capturing the vast amounts spent
on high-margin, high-end goods by gamers, video editors, and others who
want its performance and video capabilities. As today's
highest-performance SSDs and super-high-resolution displays drop in
price, I expect more people will find Thunderbolt 5's capabilities
useful.

A Brief History of Thunderbolt

Thunderbolt 5 is the latest entry in an evolutionary tree that starts
with Thunderbolt 3, the first version of the standard to use the USB-C
connector type developed by the [5]USB Implementors Forum (USB-IF).
That group maintains the USB standard and is in a kind of cooperative
war with Intel's Thunderbolt. The USB-IF and Intel adopt and expand on
each other's improvements through open licensing and other principles
that have enhanced both standards. I doubt we'd see this pace of
improvement without this 'co-opetition.'

Thunderbolt 3 provided a new baseline of 40 Gbps in each direction,
though there were cabling issues. Thunderbolt 3 cables include
circuitry that renders them either passive or active, which refers to
the type of signaling chips built into the cables. Active cables are
more expensive but can carry 40 Gbps at up to 6.6 feet (3 meters),
whereas passive cables max out at 20 Gbps above 20 inches (0.5 m).

Only some Thunderbolt 3 cables had to carry up to 100W. Weirdly, any
Thunderbolt 3 cable that allowed over 15W had to support up to 100W.
There was also the problem that Thunderbolt 3 active cables throttled
USB 3 to the older USB 2.0 data rate of 480 Mbps for complicated
backward compatibility reasons. That's why you could encounter
Thunderbolt 3 cables that, when plugged into USB 3 on one end or the
other, would provide unexpectedly poor data rates. You couldn't look at
a 15W or active cable and typically know what it was. (See, for
instance, '[6]How Some Thunderbolt 3 Cables Underperform with USB-only
Drives,' 23 August 2017. Some charging-focused cables, like the Apple
USB-C Charge Cable mentioned above, still only carry USB data at USB
2.0's rate for complicated reasons.)

Thunderbolt 4 upgraded all the optional and 'by-the-way' features in
Thunderbolt 3 and made them mandatory. This included mostly ditching
the active/passive cabling situation. All computers with Thunderbolt 4
must have at least one Thunderbolt port that provides 100W of power.
Likewise, all Thunderbolt 4 cables must be capable of carrying 100W.
All Thunderbolt 4 cables are active and must carry 40 Gbps at up to 6.6
feet when connected to capable devices on both ends.

When USB4 shipped'note the lack of a space in its name'it incorporated
all the Thunderbolt 3 specs alongside backward compatibility with USB
2.0 and 3.x. This move allowed a single cable to support both
Thunderbolt 4 and USB4! At last! (The only oddity is that some cables
over about 32 inches (0.8 m) max out at 20 Gbps with USB4.)

After the awkwardly named USB-IF update to USB4, called USB4 2.0, was
announced in September 2022, Intel came out with its own news about
Thunderbolt 5 (then called 'next-generation Thunderbolt') in October
2022. USB4 2.0 was released as a specification to the industry in June
2023, and Thunderbolt 5 followed in September 2023. As you may have
noticed above, Thunderbolt 5's data transfer and power delivery specs
sound a lot like USB4 2.0's specs'in fact, Thunderbolt 5 adopted those
specs from USB4 2.0.

Yes, that's right. Despite Intel's 2022 press release titled '[7]Intel
Leads Industry with Next-Generation Thunderbolt,' Thunderbolt 5's
improvements boil down to incorporating USB4 2.0'announced just before
Thunderbolt 5 in October 2022'and DisplayPort 2.1.

Glenn Fleishman is the author of [8]Take Control of Untangling
Connections, a comprehensive guide that elaborates on the above
standards. The book primarily focuses on assisting you in selecting the
best hardware, peripherals, and cables to achieve optimal results while
also addressing issues related to incompatibilities and slow data
rates.

References

1. https://www.chargerlab.com/first-batch-of-thunderbolt-5-devices-launched-includes-laptops-docking-stations-hard-drives-and-cables/
2. https://www.cablematters.com/Blog/DisplayPort/what-is-displayport-21?srsltid=AfmBOoow7vAGCrGUZAVQVwmXk7Cm-9j11vVVbyJG8RqFda65edhuu9Tt
3. https://www.apple.com/shop/product/MYQT3AM/A/240w-usb-c-charge-cable-2-m
4. https://www.apple.com/shop/product/MC9C4AM/A/thunderbolt-5-usb%E2%80%91c-pro-cable-1-m
5. https://www.usb.org/front-page
6. https://tidbits.com/2017/08/23/how-some-thunderbolt-3-cables-underperform-with-usb-only-drives/
7. https://www.intel.com/content/www/us/en/newsroom/news/intel-leads-industry-next-generation-thunderbolt.html
8. https://www.takecontrolbooks.com/untangling/?pt=TIDBITS