Opinion: What does Intel’s Thunderbolt 3 news mean for eGPUs?

eGPU Resources, External Graphics Card 7 Comments


Recently, Intel announced some big news in the Thunderbolt 3 ecosystem.  Below I discuss why I believe they are a big step forward for Thunderbolt eGPUs.

Thunderbolt in the CPU

“…With this vision in mind, Intel is announcing that it plans to drive large-scale mainstream adoption of Thunderbolt by integrating Thunderbolt 3 into future Intel CPUs…”

One of the biggest parts of this Thunderbolt 3 news is that Intel’s CPUs will feature the controller in the CPU its self.

No longer does Thunderbolt 3 have to only feature on high-cost, premium notebooks, but all machines of all price ranges.  This will bring eGPUs into the mainstream. 


More customers for OEMs

This opens up whole new markets for eGPU enclosure makers, which as of present have been mostly targeted towards the niche end of things. However, once Thunderbolt 3 is present on $350 bargain-basement laptops from Best Buy, or Argos, the market for a ~$350 all-in-one enclosure + GPU pops up.

This could be marketed towards casual gamers who are considering a console, allowing them to upgrade their cheap laptops into capable gaming machines for e-Sports games such as Overwatch. A 1050 combined with a i5-7500U makes a capable gaming machine for many.


More choice for ENTHUSIASTS

As well as benefiting the low end, inclusion of Thunderbolt 3 on a wider variety of machines gives enthusiasts a wider choice machine. Whilst the past year has seen a huge improvement in Thunderbolt 3 availability in the high end, for example on the new premium Lenovo laptops, support is still not perfect.

On-die Thunderbolt 3 would make missing Thunderbolt 3 from a high end product inexcusable.


Performance Improvements

In addition, this could bring a solution to three nagging performance issues of Thunderbolt 3:

  1. the DMI bottleneck. If the Thunderbolt 3 controller is on the die of the CPU, and does not have to share bandwidth with the chipset over the DMI (a x4 3.0 link on Sky Lake/Kaby Lake), one of the major performance bottlenecks for Thunderbolt 3 gets eliminated. This bottleneck is evident on all current Thunderbolt 3 notebooks except for one – the 15″ Macbook Pro – which connects it’s Thunderbolt 3 controller directly to the CPU.  This is shown pictorially here.
  2. Thunderbolt 3 throttles PCIe traffic from 32Gbps down to 22Gbps at the device chain level.  10Gbps seemingly reserved for guaranteed USB-C 3.1 bandwidth in their dual-port Thunderbolt 3 controllers.  Future eGPU-centric Thunderbolt products could instead dedicate a full 32Gbps for the eGPU PCIe traffic.
  3. Improve Thunderbolt controller encoder/decoder speed that is dragging down performance when compared to a direct PCIe link. Example is shown here.

Thunderbolt 3 traffic examples

Above: From pg 6 of Intel’s Thunderbolt 3 Technology Brief, Thunderbolt 3’s maximum 22Gbps PCIe traffic ‘Data’ to/from the host. This is considerably less than 32Gbps; the bandwidth of 4-lane PCIe 3.0 the Thunderbolt 3 controller takes as input.


Royalty Free

“next year Intel plans to make the Thunderbolt protocol specification available to the industry under a nonexclusive, royalty-free license”

Currently, we have no idea how much Thunderbolt 3 costs per device for a vendor. However, despite eGPU enclosures being low-margin devices, prices are extremely high in comparison to their BOM cost.

It is hard to find an eGPU enclosure for under $300, and a complete desktop PC can be purchased for just over that. Despite the huge difference in volume, I certainly think it is possible to produce a budget eGPU enclosure for $100 BOM cost, so even leaving $100 for profit among OEM, distributor, and distribution costs, that still leaves $100 uncounted for. (Disclaimer: I have no experience in product creation and distribution, so I may be completely off whack).

Cutting the royalty out of the equation, along with higher volumes, should really help bring down the cost of enclosures. It will just be down to the enclosure producers to pass on the cost savings to the consumers.

However, the announcement does not state that certification will be free. Thunderbolt 3 enclosure manufactures will still likely have to send everything to Intel’s testing facility in Israel to be verified. Intel might want Thunderbolt 3 everywhere, but I doubt they want to compromise quality of experience too much as a result.

Releasing the Specification

“next year Intel plans to make the Thunderbolt protocol specification available to the industry under a nonexclusive, royalty-free license”

A very exciting part of the announcement is that the Thunderbolt 3 specification will be released to the industry.

However, it is important to note the wording of this. Industry does certainly not mean public, and we do not know which industry this may be. It could well be only the semiconductor industry, meaning we see a few more Thunderbolt 3 chips from well-known manufactures such as Cypress Semiconductor.

This is also hammered home by the fact it is still very much a license, which the specifics of us may never be known, but undoubtedly will include some protections for the Thunderbolt 3 user experience.

Sadly, think this means we are not going to see Aliexpress and Taobao with sub-$100 PCBA products like EXP has for Expresscard. I think the biggest impact here will be seen in Thunderbolt 3 docks that do not have eGPU functionality; we may see Thunderbolt 3 controllers that only support the DP and USB parts of Thunderbolt 3 for cost reduction.

Transferring 40Gbps data over a somewhat reasonably priced copper cable is no mean feat, so the chance of implementation by unknown brand Chinese outfits is small.

Recent Developments – Apple

As of the 5th June, Apple has announced eGPU support. This gives an overnight boost to the popularity and successful-ness of the eGPU.  

It’s impossible to know if Apple knew about Thunderbolt 3 becoming on-die and royalty free, but given their closeness in developing the standard it would be surprising if this announcement’s timing is completely coincidental.

Whilst Apple has its own dev kit, we have seen any eGPU enclosure with a RX580 and TI83 USB-C chip working as plug and play as the dev kit. This is great news for the cross compatibility of eGPUs and further encourages competition between enclosure makers.

Recent Developments – HP

HP has recently announced its own eGPU, which is both featureful and has its RRP set at only $299

HP eGPU on the front page of The Verge

This made the front page of many tech news sites, with The Verge even going as far to say there is a Hype for eGPUs. 

The HP enclosure is as fully featured as consumer eGPU enclosures get these days, with 60W or more changing power for the Attached notebook, and USB and Ethernet ports for docking, all for $299.

This shows the power of large OEMS who have a large R&D budget. HP has not had to include all its R&D costs in the price of the enclosure unlike say Inxtron/Akitio where their Thunderbolt 3 products make up a large amount of its lineup.

Whilst on the large size, the pricing and promotion from such a large OEM is a definate plus to eGPUs and shows that they believe the market is there.


Whilst it is important to take the benefits of this announcement with a pinch of salt, some of the changes present a bright future for Thunderbolt 3 eGPUs.

All of the changes discussed above serve as a huge boost for the entire Thunderbolt 3 ecosystem, a long way from its very closed start and various miss-steps along the way.

I do not think it will bring us back to the stage of cheap DIY eGPUs from the days where ExpressCard reigned supreme, it serves to bring us a wider selection of Thunderbolt 3 hosts, and cheaper off-the-shelf enclosures.

Very major players in the computing world are now supporting eGPUs, bringing out their own hardware, and for the most part keeping things cross compatible.

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I hope there be some Thunderbolt 3 PCB on sale later. Most Thunderbolt 3 cases are ugly and unreasonable fat.


Hey, enclosures have feelings too. Don’t call them fat and ugly! 😉


Haha. Yeah, they are not fat just big boned with too much soda gas inside. 😆


I would totally want to see laptops less than $1,000 with full speed thunderbolt 3 ready to go with egpu enclosures! And without dedicated graphics so it doesn’t cost too much. I hope it happens!

Any idea how long until more news on this???


Since the vision is mainstream adoption, I wonder when motherboards for AMD processors will get Thunderbolt, now that Intel has made it royalty free.  I’ve heard it’s more up to the motherboard manufacturer rather than AMD to make the controller for Thunderbolt, but what would AMD need to do to make sure chipset implementers go ahead and put TB3 in their desktop boards and laptops?


I may add (as often before) that the H2D Bandwidth is not very important for performance. If we have look at this post:

It’s is becomes quite clear.