Thunderbolt 6!

[jimthing]

Q: Thunderbolt 6 – is there actually going to be a version 6?

What comes after Thunderbolt 5? (sarcasm aside...yes obviously version number "6", lol!)

Given the original Thunderbolt spec (aka "Light Peak") was aimed to reach speeds of 100Gbps over its lifespan of versions, and TB5 already does 80 or 120Gbps (depending on mode), is there another protocol or standard waiting in the wings to take over as the next connection standard? And will it (presumably) remain using the same USB-C as its connector, just as TB3 to TB5 use, too?

Or perhaps more likely, as the spec was made royalty-free and custodianship of the Thunderbolt protocol transferred from Intel to the USB Implementers Forum, perhaps Thunderbolt will be obsoleted as a term, with USB 5 (at whatever speed they can do next) taking over as 'the next port'?


If the dates of previous versions are anything to go by, it may arrive as early as 2027, hence asking the question now.
See below the dates of the previous versions (though sometimes Macs took another year afterwards to get the new ports):

YEAR	VERSION	CONNECTOR	SPEED	PCIe	OTHER
2011	TB1	miniDP	20 Gbit/s total (10 Gbit/s each channel)	2.0 ×4	DP 1.1a
2 years
2013	TB2	miniDP	20 Gbit/s total	2.0 ×4	DP 1.2
2 years
2015	TB3	USB-C	40 Gbit/s bidirectional	3.0 ×4	DP 1.2, USB 3.1 Gen 2
5 years
2020	TB4	USB-C	40 Gbit/s bidirectional	3.0 ×4	DP 2.0, USB4
3 years
2023	TB5	USB-C	80 Gbit/s bidirectional	4.0 ×4	DP 2.1, USB4
...
4/5 years (?)
2027/8 (?)	TB6 (?)	USB-C (?)	100/160/200 (?) Gbit/s bidirectional	5.0 ×4(?)	DP 2.1b (?), USB5 (?)

Just wondering if anyone more clued-up about such things can enlighten those of us less knowledgeable on this. Or otherwise, at least it might be an interesting speculation topic for the Apple geeks around here (me included, lol!).


EDIT: On the related topic, one has to wonder if optical Thunderbolt cables (all those typically over 3m max offered by copper) are ever going to arrive, as the last ones available were TB3 40Gbps ones (from Corning et al.).
No TB4 or TB5 optical cables have been released for sale thus far.

 

[joevt]

TB5 is 40 Gb/s per lane. 2 lanes per direction. Optionally 3 lanes for one direction + 1 lane for the other direction in asymmetric mode.

To understand where Thunderbolt might go after that, you might consider looking at other serial type communications standards such as PCIe:
PCIe 6 is 64 GT/s per lane.
PCIe 7 is 128 GT/s per lane.
PCIe 8 is 256 GT/s per lane.
https://en.wikipedia.org/wiki/PCI_Express

Or Ethernet:
https://en.wikipedia.org/wiki/100_Gigabit_Ethernet

 

[cbum]

Sorry, but what is the difference between GB/s and GT/s?

 

[maflynn]

Sorry, but what is the difference between GB/s and GT/s?

Here's what I found

• GT/s (Gigatransfers per second): The raw number of transfer operations or clock signals sent per second by a hardware interface. It counts every bit sent on the wire, including control and error-correction overhead bits.
• GB/s (Gigabytes per second): The actual amount of usable user data transferred per second. It translates the raw transfers into physical bytes after removing encoding overhead

I've only seen GT/s on a handful of YT influencers. For me GB/s makes more sense to my tiny brain

 

[deconstruct60]

Q: Thunderbolt 6 – is there actually going to be a version 6?


TB 4 .... USB 4 TB 5 .... USB 4 TB 6 ? ... USB 5?

Actually TB 5 is tecnically coupled to USB 4 version 2.0

Thunderbolt is driven directly by Intel ( it is just an Intel branding mechanism now) and USB baseline upgrades.

Intel has been about eye-ball deep in trouble the last couple of years. They have far ,f ar , far bigger 'forest fire' issues to fight than a new Thunberbolt. I wouldn't hold my breadth on a version 6 coming.

The RAM-apocalypse (and NAND and increasing SoC fab processing prices) probably puts USB on hold also. A major sub faction of the USB-IF committee don't like having to implement higher cost ports. Already have higher priced other components nobody wants. About nobody wants the systems to get even more expensive for the next couple of years.

Ab best might some small revisions from USB for a USB 4 version 3.0 that tweaked some optional stuff more standard. That might get a TB '5.5' or TB 5b, but I doubt a 6.

It looks like Intel is finally going to put TB 5 in the base SoC in 2027 "Nova Lake" SoCs. So even Intel had not fully adopted TB v5 across a major portion of their line up. There are probably not in any big hurry to have to try to chase something faster as a built-in for a while. AMD is doing about as little as possible to get to TBv5 and now control a substantively large portion of the PC market. Qualcomm ... no TB. Nvidia might grab more share ... again no TB.

The days of Intel making the PC market choke down a new port faster than they want are over. Apple has been incrementally dragged their feet on TBv5 across the line up also.

Might get TB '5.5' with more standardized RDMA , but I suspect that won't happen. However, if spun as a "getting on the AI clustering hypetrain' with sufficient effort maybe. [ Still... doubt AMD is going to 'buy into' that. They already have Ethenet RDMA components to sell (and so does Nvidia and Intel. ) .. ]

Just wondering if anyone more clued-up about such things can enlighten those of us less knowledgeable on this. Or otherwise, at least it might be an interesting speculation topic for the Apple geeks around here (me included, lol!).

'Thunderbolt' at this point is mainly USB N with less stuff optional. USB-IF usually leaves the more harder/more expensive features to implement as optional. Thunderbolt just makes it more uniform (mandates some features as required taking them off the 'optional' list. )

EDIT: On the related topic, one has to wonder if optical Thunderbolt cables (all those typically over 3m max offered by copper) are ever going to arrive, as the last ones available were TB3 40Gbps ones (from Corning et al.).
No TB4 or TB5 optical cables have been released for sale thus far.

The asymetrical mode of USB 4 version 2.0 (and TBv5) makes doing the optical more tricky (and expensive).
Have to be able to 'reverse' a lane. Or double up all the lanes and just underutlize 3 of them.

The problem generally though is how many system vendors are implementing USB 4 version 2.0?
I'm not sure AMD has moved to 'version 2.0'. And I think the asymetrical mode might technically be optional. If so even if do v2.0 may not do that. I think AMD is OK with advanced DisplayPort and HDMI connections.

Apple primarily wants THunderbolt as a one port wonder docking station connection. That means providing power. Optical doesn't do power which is a major reason it stopped being "Light peak".

Intel,AMD,Nvidia, etc are looking at photonics (optical ) to hook together nodes in clusters. I suspect that is where the most of Intel's 'optical' effort is going to go toward. Not consumer PC stuff. [ And AI driven "Spend money like drunken sailors'" is having impact in optical components world also.
https://www.tomshardware.com/tech-i...sphide-shortage-will-become-worse-than-memory
]


P.S. hidden behind a paywall

https://www.tomshardware.com/peripherals/usb/usbs-next-decade

 

[deconstruct60]

TB5 is 40 Gb/s per lane. 2 lanes per direction. Optionally 3 lanes for one direction + 1 lane for the other direction in asymmetric mode.

To understand where Thunderbolt might go after that, you might consider looking at other serial type communications standards such as PCIe:
PCIe 6 is 64 GT/s per lane.
PCIe 7 is 128 GT/s per lane.

It gets substantively harder because faster PCI-e standards typically come with shorter distance limits but Oculink x4-x8 with PCI-e v5 and maybe v6 just does better data bandidth to a PCI-e card. (e.g., discrete GPU.) . Apple has largely walked away from dGPUs. The rest of the PC market has not.

Oculink is no where near as common on general market PC sytems , but system deployment has gotten wider.

Displays that have more than one input connector can use a HDMI or DisplayPort to hook to an eGPU for the video output traffic. Oculink not carrying it does not matter.

Apple has more of a 'Display Docking Station' solution space focus.

Better Oculink makes the addressable solution space smaller for Thunderbolt. Oculink doesn't have to be a TB 'killer' to slow it down.

 

[joevt]

Sorry, but what is the difference between GB/s and GT/s?

See the notes section in the wikipedia page for PCI Express. It says:

Notes

1. In each direction (each lane is a dual simplex channel).
2. Transfer rate refers to the encoded serial bit rate; 2.5 GT/s means 2.5 Gbit/s serial data rate.
3. Throughput indicates the usable bandwidth (i.e. only including the payload, not the 8b/10b, 128b/130b, or 242B/256B encoding overhead). The PCIe 1.0 transfer rate of 2.5 GT/s per lane means a 2.5 Gbit/s serial bit rate; after applying a 8b/10b encoding, this corresponds to a useful throughput of 2.0 Gbit/s = 250 MB/s.

In the case of PCI Express, a transfer is a single bit on the wire.
For PCIe gen 1 and gen 2, it takes 10 transfers to encode 8 bits of data.
For PCIe gen 3, gen 4, and gen 5, it takes 130 transfers to encode 128 bits of data.
PCIe gen 1 to gen 5 use NRZ signals https://en.wikipedia.org/wiki/Non-return-to-zero
PCIe gen 6 uses PAM-4 https://en.wikipedia.org/wiki/Pulse-amplitude_modulation

Different versions of USB (from USB 1.1 to USB4 2.0 aka Thunderbolt 5) use different encodings https://en.wikipedia.org/wiki/USB

NRZ and NRZI use 2 diferrent levels in a single transfer so one transfer is a single bit.
PAM can use 3 or 4 different levels in a single transfer. So multiple transfers are used to encode multiple bits.

If PAM 3 use 3 levels, then 2 transfers encodes 9 different values, 3 transfers encodes 27 values, 4 transfers encodes 81 values, etc.
The USB wikipedia page says 7 transfers encodes 11 bits of data.
3^7 = 2187
ln2(2187) = 11.095 bits per 7 transfers.
ln2(3) = 1.585 bits per transfer.

For PAM 4, one transfer is at most 2 bits. For PCIe 6, some bits are used for FEC (forward error correction).

 

[jimthing]

Thanks for the info. Good though all the above background info is, it doesn't really answer the central question of what's next?

Sure whatever it is may be delayed, and sure no organisation may be interested in the short term. But something has to come next at some point, as <companies: eg. Apple> always have to sell us 'the next big thing'.

From the sounds of things, no one (publicly) knows. Oh well.

 

[EugW]

What I would find even more exciting as a next step is A-series SoCs getting USB 4. That would make for a killer MacBook Neo. 2030 or later?

 

[theorist9]

TB5 is 40 Gb/s per lane. 2 lanes per direction. Optionally 3 lanes for one direction + 1 lane for the other direction in asymmetric mode.

To understand where Thunderbolt might go after that, you might consider looking at other serial type communications standards such as PCIe:
PCIe 6 is 64 GT/s per lane.
PCIe 7 is 128 GT/s per lane.
PCIe 8 is 256 GT/s per lane.
https://en.wikipedia.org/wiki/PCI_Express

Or Ethernet:
https://en.wikipedia.org/wiki/100_Gigabit_Ethernet

Following this idea, I asked ChatGPT 5.6 Sol to create a speculative table. Here's what it came up with by assuming that TB6 would be matched to the next PCIe generation in the Thunderbolt progression (5.0), and that the ratio of PCIe/TB bandwidth for TB6 would be the same as it was for TB2 through TB5:

It added the following:

"So an eventual next-generation combination of approximately

PCIe 5.0 ×4 → 128 Gb/s PCIe → 160 Gb/s Thunderbolt

would be very logical.

But I would not call it a prediction with high confidence, because the Thunderbolt number is ultimately constrained by the external cable PHY, not by PCIe. Intel could, for example:

• move to PCIe 5.0 ×4 while retaining an 80-Gb/s external link for some generation;
• choose some external rate other than 160 Gb/s;
• change the lane architecture or encoding;
• wait for a future USB4 revision before defining the next Thunderbolt generation;
• or make another TB3→TB4-style generation that improves requirements/features without doubling the PHY rate."

 

[drrich2]

I've only seen GT/s on a handful of YT influencers. For me GB/s makes more sense to my tiny brain

It's hard enough to keep the 'b' (bits) and 'B' (Bytes) in Mbps/MBps straight, especially since it's not a 10-base conversion (guess the metric-folks didn't get to rule?). Then there's the M (mega) vs. G (giga); please don't give us yet another unit speed abbreviation to juggle.

While TB 6 would be interesting in a 'faster is always better' way, how much demand is there? How many people would benefit?

Now, once your SSD's cache exhausts, an external TB5 drive's speed can drop substantially. I assume TB 6 would have the same issue, if you're moving massive files.

Networking influencers seems to still consider 10 Gbps ethernet 'blazing fast,' and adequate for people editing video.

I don't get the sense Apple is keen to encourage people to make an external drive their startup (and main) disc, though it can be done.

Gen. 5 SSDs are more expensive, and right now SSD prices are...ridiculous.

EDIT: On the related topic, one has to wonder if optical Thunderbolt cables (all those typically over 3m max offered by copper) are ever going to arrive, as the last ones available were TB3 40Gbps ones (from Corning et al.).
No TB4 or TB5 optical cables have been released for sale thus far.

Apple primarily wants THunderbolt as a one port wonder docking station connection. That means providing power. Optical doesn't do power which is a major reason it stopped being "Light peak".

This all raises the question of whether 'the next big thing' (whatever it is) in high-speed data transmission will be something other than Thunderbolt, not a new iteration.

At the Thunderbolt 4 speed class, some Cat. 8 ethernet cable could fill the bill...if you had devices with ethernet capabilities that could take advantage of 40-Gbps speeds. If you don't need power delivery (and hey, there's POE - Power-Over-Ethernet if you do!), that could be much longer and more cost effective vs. Thunderbolt cables.

Beyond that, what about fiber? Maybe the next big thing isn't Thunderbolt at all.