A feature in over 100 million computer systems worldwide, across multiple ecosystems, Intel's Thunderbolt I/O has been a fixture for premium computing since its inception in 2011. Chiefly known for being integral to Apple's iMac range (which had some level of exclusivity early on), adoption in the PC-space has been a little slower; nonetheless the number of Thunderbolt-compatible external devices has ballooned to 250, despite both its cost and narrow install-base compared to both USB 3.0 and eSATA.
At Computex 2015 this past week Intel unvieled their plans for the third major iteration to their Thunderbolt technology, bringing with it the first major connect redesign, new communications bandwidth and therefore the potential for a whole new set of devices beyond the innovation we saw in Thunderbolt's first two generations.
Introducing Thunderbolt 3.0
Thunderbolt 3.0, codename Alpine Ridge, is slightly more than a generational improvement over Thunderbolt 2.0. From the get-go Intel utilised a connector type based on mini-DisplayPort, a convenient standard given the capabilities of Thunderbolt at the time. With the third generation Intel are moving to the cutting-edge USB Type-C connector, getting on board early with the new high-speed USB protocol and building on that standard's capabilities. However that's not without its challenges.
Thunderbolt 3.0 needed to provide I/O protocols for Thunderbolt, DisplayPort and PCI-Express, all while also acting as a host controller for USB 3.1 for standard USB devices with a Type-C connector. In theory it would have been possible (although enormously complicated) to tinker with a Type-C connector to add additional wiring for Thunderbolt-only functionality, much like USB 3.0's implementation and interaction with legacy ports, but that would add cost to both connector and cable. Intel compromises in Thunderbolt 3.0 by offering *either* USB-C or 40Gbps Thunderbolt 3.0 over the same wires. If USB is dectected it will revert to a USB host controller, and without passing through a 'Thunderbolt' emulation layer.
In so doing, Intel aim for Thunderbolt 3.0 to provide the best of both worlds: massive USB Type-C device compatibility, and high-bandwidth Thunderbolt I/O for those devices which need it.
Thunderbolt 3.0 Capabilities
In addition to a more ubiquitous connect standard Thunderbolt 3.0 also offers generational improvement over 2.0. Bi-directional bandwidth is now up to 40Gbps from 20Gbps, and it now supports PCI-Express 3.0 signalling rather than PCI-E 2.0. In total, Thunderbolt 3.0 is capable of over four times the data throughput and twice the video bandwidth.
In terms of DisplayPort, a single Thunderbolt 3.0 cable can provide two DisplayPort 1.2 streams (8 lanes). This allows transmission of two 4K@60Hz video streams, or support for one 5K@60Hz display. It's noteworthy however that Thunderbolt still supports DisplayPort 1.2 rather than ther newer DP 1.3 specification; Intel state that this is because the new standard remains relatively poorly supported on monitors, but it does seem a little odd considering that USB Type-C is still in its infancy, yet support.
Power
Power is another major boost for Thunderbolt 3.0, leveraging the improvements brought about by the use of the USB Type-C connector. Purely as a power connector the USB Power standard for USB Type-C specifies supply of up to 100W to the notebook/laptop for charging or Uninterruptable Power Supply usage, and can also supply 15W to the peripheral. Not only that, these two modes are independent.
The increased functionality boosts the potential range of devices suitable for Thunderbolt. Value to the mobile space is obvious, but we're also curious to see what the additional bus power can bring to the desktop space.
Daisy-chaining Devices
One of the major selling points of Thunderbolt has been the ability to daisy-chain devices, and Thunderbolt 3.0 augments this by offering inherited functionality. Now a second port on a device on the chain will offer the same range of functionality as the original computer port.
More Possibilities
The evolution of Thunderbolt has come at a time when there is ever-greater emphasis on high resolution displays, and so it's now wonder that Intel sees this as a fillip for the new standard. The retail price of external 4K displays for use as secondary displays for notebooks etc. continues to drop, with some now available below the $1000 mark. With Thunderbolt you have the opportunity to run 4K video, external high-bandwidth storage and a main notebook display with a simple configuration, all using the same connection standard.
Furthermore single cable docking increases the power and flexibility of a Thunderbolt 3.0 dock. Such a device can offer a wide range of display and I/O options, connected through one Thunderbolt 3.0 cable, and also supply up to 100W of power to the notebook. Such a dock could also provide USB 3 functionality, acting as a host device which would then communicate to the notebook via Thunderbolt.
And then there's external graphics...
External Graphics
The use of discrete external graphics has been mooted with Thunderbolt since its introduction to the PC. By offloading high-power graphics operations to a discrete, removable and independently powered card you not only greatly improve notebook battery life but also make the notebook itself smaller and lighter whilst 'on the go' when high-power graphics are unnecessary. Thunderbolt makes use of high-bandwidth PCI-Express signalling, the only impediments therefore are hardware based.
Limited forays into creating discrete external graphics enclosures from the likes of MSI didn't gain much traction, but as the capabilities have improved so the potential for the feature has slowly been creeping upwards. Thunderbolt 3.0 allows for a far more powerful, stationary dock with discrete gaming graphics capability that can take advantage of the improved bandwidth on offer from the updated standard.
It turns out that plans for just such a range of graphics docks are in the works, where Intel have partnered with AMD to clear any technical hurdles and certify the solution to Intel's rigorous demands. Although NVIDIA graphics will likely be supported at some point in the future their focus is on launching with AMD support.
Networking
Lesser trumpeted functionality being made more broadly available with Thunderbolt is what they're calling '10Gb Ethernet for Free'. With Thunderbolt 3.0 and two systems can be directly connected and communicate at up to 10Gbps, plus the feature will be available cross-platform and between Windows, Mac and Linux devices.
Similar networking modes are available with Thunderbolt 2.0 but Intel have commented that support is spotty and often both driver and firmware dependent. Thunderbolt 3.0 aims to be far more comprehensive.
Cable Options
Intel are planning three different cable options for Thunderbolt 3.0, targeting three markets (and price points).
1.) Passive 20Gbps Copper. A relatively low-cost option based on the USB Type-C cable, it's most suited to consumer markets with only limited high-bandwidth requirements and small distances between devices. The maximum cable length is around 2 metres, but a range of options are available.
2.) Active 40Gbps Copper. Higher manufacturing costs required for an active connector are passed on to the owner, and are really for situations which have very high bandwidth demands. Strangely enough DisplayPort isn't supported; Intel believe that those who use Thunderbolt 3.0 for displays will be catered to by the passive 20Gbps option.
3.) Active 40Gbps Optical. The premier (and most expensive) option, it's currently under development for a 2016 launch. Offering full bandwidth and the entire range of Thunderbolt 3.0 capabilities, it's also the best option for enterprise environments that require cabling of up to 60m.
2.) Active 40Gbps Copper. Higher manufacturing costs required for an active connector are passed on to the owner, and are really for situations which have very high bandwidth demands. Strangely enough DisplayPort isn't supported; Intel believe that those who use Thunderbolt 3.0 for displays will be catered to by the passive 20Gbps option.
3.) Active 40Gbps Optical. The premier (and most expensive) option, it's currently under development for a 2016 launch. Offering full bandwidth and the entire range of Thunderbolt 3.0 capabilities, it's also the best option for enterprise environments that require cabling of up to 60m.
Confusion over the capabilities of the Active 40Gbps Copper cabling options notwithstanding, the largest bugbear for legacy users of earlier generations of Thunderbolt will be one of backwards compatibility. The connector used is changing substantially, and although an adapter is under development it will add additional expense to an already pricey upgrade.
Intel are continuing with their certification process, and Thunderbolt-certified devices will continue to make use of the 'lightningbolt' logo. However there will be no distinction in labeling from TB 2.0 to 3.0, so you'll need to inspect the actual port or consult the manual to determine an appropriate connector.
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Thunderbolt 3.0 should begin shipping in late 2015, whilst production and availability will ramp up throughout 2016. The launch is likely to coincide with the launch window of Intel's Skylake desktop platform; the technology however is independent of Skylake and hence may appear in non-Skylake chipsets such as revisions or augmentations to the HEDT Haswell-E platform.
