Friday, October 20th 2023

Intel 14th Gen Core Desktop Processors Don't Support Thunderbolt 5
Intel earlier this week updated its desktop processor product stack with the introduction of the 14th Gen Core "Raptor Lake Refresh" processors. During our coverage of the processor, we erroneously mentioned that the processor supports the upcoming Thunderbolt 5 connectivity standard. Intel reached out to us for a correction, which revealed an interesting detail. Apparently, 14th Gen Core desktop processors do not support Thunderbolt 5, even though Intel has their own TB5 controller design codenamed "Barlow Ridge". However, these won't arrive before Q1 2024, the currently shipping "Maple Ridge" controller has only support for Thunderbolt 4. But even once Barlow Ridge is available, they will not be compatible with "Raptor Lake Refresh" socketed desktop processors.
Intel announced the Thunderbolt 5 standard in September, around the same time, it provided a technical reveal of its upcoming Core "Meteor Lake" mobile processors. The new standard provides a generational doubling in bandwidth to 80 Gbps (per direction), but relies on an exotic new feature called Bandwidth Boost. With this feature enabled, users get 120 Gbps of bandwidth in a particular direction, and 40 Gbps on its opposite direction.Bandwidth Boost should come in handy when, for example, you are importing a large data set from a Thunderbolt 5-based external storage device to your local machine. In such a case, the receiving (Rx or inbound) bandwidth is boosted to 120 Gbps, while reducing the transmission (Tx or outbound) bandwidth to 40 Gbps. When exporting a large amount of data to this external Thunderbolt 5 storage device, the roles are reversed, where the Tx bandwidth is boosted at the expense of the Rx bandwidth.
It's important to take a moment to understand how Intel arrives at 80 Gbps as the default per-direction bandwidth of Thunderbolt 5, even when the underlying PCIe bandwidth of PCIe Gen 4 x4 adds up to 64 Gbps per direction—Thunderbolt is a complex bus, which combines a number of links besides PCIe, such as DisplayPort, which is how it arrives at its advertised bandwidth. So 80 Gbps is really just 64 Gbps of underlying PCIe bandwidth, and 120 Gbps is really just 96 Gbps, and the current Thunderbolt 4 that boasts of 40 Gbps/direction is really just 32 Gbps/direction PCIe.
Thunderbolt and USB4 are PCIe-based serial interconnect standards. Each PCIe lane has physical wiring for Rx and Tx. The way we understand Thunderbolt 5 Bandwidth Boost to work, for the ability to push 120 Gbps through a PCI-Express 4.0 x4 connection between the "Barlow Ridge" controller and the processor's PCIe root complex, the root complex should be able to re-task both sub-lanes of two of the four PCIe lanes for either purely-Tx or purely-Rx. This probably requires some awareness at the end of the PCIe root complex that's part of the processor's uncore.In the Intel slide above, the company details how Bandwidth Boost works at the Thunderbolt 5 link layer. Two 40 Gbps links per direction normally make up the 80 Gbps per-direction bandwidth of Thunderbolt 5. With Bandwidth Boost enabled, three out of four links are loaded toward one direction to make 120 Gbps, while the last link is in the opposite direction. As for which direction gets the Bandwidth Boost depends entirely on the application, as detailed in the examples above. You get get a 120 Gbps high-speed transmit with a 40 Gbps receive, or a 120 Gbps high-speed receive with a 40 Gbps transmit. The second image drawn by us, illustrates how the PCIe backend works between the Thunderbolt 5 host controller and the PCIe root complex.
Without this uncore-level awareness, for Thunderbolt 5 to be able to push 120 Gbps to a downstream device, there needs to be a PCIe Gen 4 x8 connection between the PCIe root and the "Barlow Ridge" host controller that can provide 160 Gbps of per-direction bandwidth, which is both undesirable and unlikely, as all prior generation discrete Thunderbolt controllers by Intel have used a PCIe x4 connection to the platform.
Intel also stated that when "Barlow Ridge" does come out in Q1 2024, it will have compatible processors at launch, without stating what those processors are. It's possible that Intel is updating its mobile processor stack, and those processors will support Thunderbolt 5 the way Intel intends it (including the Bandwidth Boost feature). Intel already provided a technical deep-dive of its upcoming Core "Meteor Lake" mobile processor, without mentioning product launch dates. The 2024 International CES (January) provides Intel with the perfect opportunity to launch new processors. Intel put out this statement as an October 19 editor's note in its newsroom article announcing the 14th Gen Core desktop processors:
Users on the 14th Gen Core socketed desktop platform can enjoy Thunderbolt 4 using motherboards or add-on cards that have Intel's "Maple Ridge" controller that's been in the market since 2020, which provides 40 Gbps per direction bandwidth. Thunderbolt 5 and AI Boost are two features that will only make it to socketed desktop platforms with Intel's next-generation processors. We know that "Meteor Lake" is confirmed not coming to socketed desktop platforms, which leaves us with "Arrow Lake-S," bound for the second half of 2024.
Intel announced the Thunderbolt 5 standard in September, around the same time, it provided a technical reveal of its upcoming Core "Meteor Lake" mobile processors. The new standard provides a generational doubling in bandwidth to 80 Gbps (per direction), but relies on an exotic new feature called Bandwidth Boost. With this feature enabled, users get 120 Gbps of bandwidth in a particular direction, and 40 Gbps on its opposite direction.Bandwidth Boost should come in handy when, for example, you are importing a large data set from a Thunderbolt 5-based external storage device to your local machine. In such a case, the receiving (Rx or inbound) bandwidth is boosted to 120 Gbps, while reducing the transmission (Tx or outbound) bandwidth to 40 Gbps. When exporting a large amount of data to this external Thunderbolt 5 storage device, the roles are reversed, where the Tx bandwidth is boosted at the expense of the Rx bandwidth.
It's important to take a moment to understand how Intel arrives at 80 Gbps as the default per-direction bandwidth of Thunderbolt 5, even when the underlying PCIe bandwidth of PCIe Gen 4 x4 adds up to 64 Gbps per direction—Thunderbolt is a complex bus, which combines a number of links besides PCIe, such as DisplayPort, which is how it arrives at its advertised bandwidth. So 80 Gbps is really just 64 Gbps of underlying PCIe bandwidth, and 120 Gbps is really just 96 Gbps, and the current Thunderbolt 4 that boasts of 40 Gbps/direction is really just 32 Gbps/direction PCIe.
Thunderbolt and USB4 are PCIe-based serial interconnect standards. Each PCIe lane has physical wiring for Rx and Tx. The way we understand Thunderbolt 5 Bandwidth Boost to work, for the ability to push 120 Gbps through a PCI-Express 4.0 x4 connection between the "Barlow Ridge" controller and the processor's PCIe root complex, the root complex should be able to re-task both sub-lanes of two of the four PCIe lanes for either purely-Tx or purely-Rx. This probably requires some awareness at the end of the PCIe root complex that's part of the processor's uncore.In the Intel slide above, the company details how Bandwidth Boost works at the Thunderbolt 5 link layer. Two 40 Gbps links per direction normally make up the 80 Gbps per-direction bandwidth of Thunderbolt 5. With Bandwidth Boost enabled, three out of four links are loaded toward one direction to make 120 Gbps, while the last link is in the opposite direction. As for which direction gets the Bandwidth Boost depends entirely on the application, as detailed in the examples above. You get get a 120 Gbps high-speed transmit with a 40 Gbps receive, or a 120 Gbps high-speed receive with a 40 Gbps transmit. The second image drawn by us, illustrates how the PCIe backend works between the Thunderbolt 5 host controller and the PCIe root complex.
Without this uncore-level awareness, for Thunderbolt 5 to be able to push 120 Gbps to a downstream device, there needs to be a PCIe Gen 4 x8 connection between the PCIe root and the "Barlow Ridge" host controller that can provide 160 Gbps of per-direction bandwidth, which is both undesirable and unlikely, as all prior generation discrete Thunderbolt controllers by Intel have used a PCIe x4 connection to the platform.
Intel also stated that when "Barlow Ridge" does come out in Q1 2024, it will have compatible processors at launch, without stating what those processors are. It's possible that Intel is updating its mobile processor stack, and those processors will support Thunderbolt 5 the way Intel intends it (including the Bandwidth Boost feature). Intel already provided a technical deep-dive of its upcoming Core "Meteor Lake" mobile processor, without mentioning product launch dates. The 2024 International CES (January) provides Intel with the perfect opportunity to launch new processors. Intel put out this statement as an October 19 editor's note in its newsroom article announcing the 14th Gen Core desktop processors:
While some processors in the Intel Core 14th Gen processor family will include support for Thunderbolt 5, Intel Core 14th Gen desktop processors, specifically, will not support it. The Intel Core 14th Gen launch announcement incorrectly said, "Intel Core 14th Gen desktop processors include support for … upcoming Thunderbolt 5 wired connectivity - supporting up to 80 Gbps of bi-directional bandwidth." Intel will share additional details on Intel Core 14th Gen CPUs that support Thunderbolt 5 at a later date.The above Intel statement says that some 14th Gen processors will support Thunderbolt 5, but not the 14th Gen Core desktop processors. Intel's "Meteor Lake" mobile processor does not come with 14th Gen Core branding, but debuts a new brand nomenclature, which leaves us with only one possibility, non-socketed 14th Gen Core processors, namely "Raptor Lake Refresh" mobile (-H and -HX). With "Meteor Lake" on the horizon, Intel may push "Raptor Lake Refresh" to the -H and -HX segments much in the same way as those segments in the 10th Gen were addressed by "Comet Lake," as "Ice Lake" handled the -U and -P segments. It's very likely that these "Raptor Lake Refresh-H/HX" processors are the ones that support Thunderbolt 5 from the 14th Gen using "Barlow Ridge" controllers, besides the upcoming "Meteor Lake" processors that have "Thunderbolt 5" integrated as part of its SoC tile.
Users on the 14th Gen Core socketed desktop platform can enjoy Thunderbolt 4 using motherboards or add-on cards that have Intel's "Maple Ridge" controller that's been in the market since 2020, which provides 40 Gbps per direction bandwidth. Thunderbolt 5 and AI Boost are two features that will only make it to socketed desktop platforms with Intel's next-generation processors. We know that "Meteor Lake" is confirmed not coming to socketed desktop platforms, which leaves us with "Arrow Lake-S," bound for the second half of 2024.
37 Comments on Intel 14th Gen Core Desktop Processors Don't Support Thunderbolt 5
Not hefty at all...
If they are planning to do an HEDT version of 14 that would be an other thing.
- this is why current desktop CPUs cannot support TB5 - neither Intel nor AMD iGPUs provide DP 2.1 signal UHBR20
- iGPU on Intel desktop CPUs and their sister -HX SKUs on laptop do not support DP 2.1 at all, hence CPU cannot provide any UHBR signal
- iGPU on AMD desktop CPUs and their sister -HX SKUs on laptop do support DP 2.1, but only UHBR10 signal, so cannot be certified for TB5
- for a motherboard vendor to certify their boards with Intel as TB5 compliant, they need to bring UHBR20 signal at 80 Gbps into the system
- only AMD W7000 PRO GPUs provide the source of DP 2.1 80 Gbps signal that could be brought into Barlow Ridge chip via DP IN port
- that's why first TB5 ports could appear next year in HEDT or workstation systems that must use AMD W7000 PRO cards
- paradoxically, this could be all-AMD Threadripper system with W7000 PRO card or Intel's system with Sapphire R., Emerald R. or RPL E2400 CPU with the said GPUs.
- TB5 on desktop will be very niche and high-end solution for a few long years, until future iGPUs support DP 2.1 UHBR20 video signal on die and until AMD and Nvidia release next gen client GPUs with the said signal for motherboards with DP IN port.
2. Bandwidth Boost conundrum - DP is the King in Tx-mode, PCIe data is secondary - without Bandwidth Boost, two NVMe Gen4 drives on both ends of TB5 cable should be able to use 64 Gbps in each direction, 128 in total
- with Bandwidth Boost, this cripples one NVMe Gen4 drive to half speed
- both of the above solutions can only work at the said speeds if there is no concurrent DP traffic saturating the remaining bandwidth on either 80 Gbps or 120 Gbps link
- Bandwidth Boost was primarily designed to benefit video data for displays; PCIe data traffic can only 'suffer' in this mode - it's more complicated, as we have downstream and upstream ports too, in addition to Tx and Rx traffic
- Intel showed on their slides that 120 Gbps link works only in Tx mode, so the feature will not work in Rx mode on downstream port (the one on the motherboard)
- this makes sense, as the feature is predominantly for DP data for more advanced displays
- the feature will work in Rx mode on upstream port only (the one on the hub or in a display, for example) - yes, your diagram makes sense
- as said above, the direction of Bandwidth Boost is Tx on downstream port and Rx on upstream port; this is due to DP traffic priority - triggering 120 Gbps link will depend on DP signal need. PCIe is secondary.
- Intel needs to clarify the moment when 120 Gbps link kicks in. It seems to me that such moment is triggered when the controller senses that video traffic needs more than 80 Gbps, for example:
- two monitors with UHBR13.5 signal that require 108 Gbps
- three monitors with UHB10 signal that require 120 Gbps
- one UBR20 and one UHBR10 monitor
- It does look like that these combinations are baked into DP protocol identifier on Barlow Ridge and managed by software.
- it's not clear how DSC would behave. It could trigger automatically once 120 Gbps are exhausted for uncompressed DP traffic
- this means that PCIe traffic could completely stop in edge scenarios when DP data takes all available bandwidth. Intel needs to clarify whether there is any minimally reserved bandwidth for PCIe traffic. There should be some, because I cannot imagine the situation when 80 or 120 Gbps are saturated with DP only and my storage peripherals cannot receive any PCIe data from PC. 3. Integrated TB5 in mobile SKUs
- Meteor Lake does not have integrated TB5. Intel confirmed that TB4 is integrated on I/O tile, up to four ports
- bizarelly, Meteor Lake does have, on Intel's slides, DP 2.1 with support for UHBR20 signal ('20G'), so this CPU is not ready for TB5 for other reasons that Intel has not disclosed
- the first mobile CPUs that could integrate TB5 on I/O tile could be Arrow Lake-H, so we are looking into ~CES 2025, but I would not be surprised if they leave it for Lunar Lake because they launched TB3 and TB4 on low-power mobility CPUs Ice Lake and Tiger Lake.
- I am curious about Gigabyte showcase laptop with RPL-HX that Intel used to present discrete TB5 solution during Innovation event
- where did they take DP 2.1 80 Gbps signal from to feed Barlow Ridge controller with?
- did they upgrade DP on Raptor Lake iGPU?
- or did they use specially prepared mobile GPU to source the signal, such as custom A770M or unreleased AMD W7000M? Curious case. No. There will be one or two halo laptops that would premier TB5 for the sake of existence in the market. TB5 will not become widespread any time soon. It will be a high-end, premium feature for a few years. It was supposed to become more widespread than ever once Intel decided to donate the spec to USB-IF. It's enough if AMD laptop has USB4 port, which usually has the same features. I have one at home with 40 Gbps. This. USB 10 Gbps (xHCI 1.1 controller) is a minimum requirement for TB5, however Intel is introducing USB 20 Gbps too, with xHCI 1.2 controller. Each data lane on TB5 is 20 Gbps, so PCIe Gen5 at 32 Gbps per lane would not fit.
Below is the review. TB4 port was not tested for USB data speed, but the silicon is capable. If anyone can get this NUC to test USB data speed, that would be great.
www.anandtech.com/show/18955/asrock-industrial-nuc-box1360pd5-review-raptor-lakep-on-the-leading-edge
How is this a different generation? Is it just to milk some money by rebranding? That's shameful intel, what the hell...
Well done what a "nice" ending for Core i-series