Questions about Thunderbolt 4 controller specifications and performance. (Resend)

[fp5849]

I have been told that the reason a peripheral Thunderbolt 4 drive enclosure (PCIe NVMe M.2 2280 M Key) provides a link speed test result of only 770MB/s to a Thunderbolt 4 Host, is because the Thunderbolt 4 controllers only supports one (1) PCIe 3.0 lane (PCIe 3.0 x1), as compared to the two (2) or four (4) PCIe 3.0 lanes supported by Thunderbolt 3 controllers.

Is this correct?

The vendor for the Thunderbolt 4 drive enclosure (PCIe NVMe M.2) also stated that the link speed test results, to a Thunderbolt 3 Host, for their other equivalent Thunderbolt 3 drive enclosures, have not been an issue because Thunderbolt 3 supports PCIe 3.0 x2, x4 lanes for Thunderbolt 3 M.2 2280 NVMe peripheral devices.

I believe the vendor is using Thunderbolt 4 Controller chip-sets.

Referencing the Intel JHL8440 Thunderbolt 4 (peripheral) Controller Product Specifications, at: https://ark.intel.com/content/www/us/en/ark/products/189982/intel-jhl8440-thunderbolt-4-controller.html

I find the following:
Supplemental Information

Description: + ThunderboltTM/USB4 peripheral support at 40G
+ Native USB Type-C interface capabilities: USB2, USB3 (10G), DP1.4 Alt-mode + Tunneling capabilities (32G PCIe, USB3(10G), 2 displays (up to DP1.4)
+ Other native interfaces: x1 PCIe 8GT/s, 1x USB3 (10G)

I/O Specifications

Port Configuration: Quad

This description for the Intel JHL8440 states:

1) Tunneling capabilities (32G PCIe ...

and

2) Other native interfaces: x1 PCIe 8GT/s...

Does "x1 PCIe 8GT/s" mean that this Thunderbolt 4 controller only supports one (1) PCIe 3.0 lane in the "link" to the Thunderbolt 4 Host controller?

Would this be why the Thunderbolt 4 drive enclosure (PCIe NVMe M.2) is only providing a link speed test result of 770MB/s to the Thunderbolt 4 Host?

If not, will someone please explain what is meant by the reference "x1 PCIe 8GT/s" reference?

It is my understanding that 8GT/s is the raw data transfer speed, in this case of 8Gb/s. Correct?

And is it correct that the "32G PCIe" refers to the minimum data transfer requirement of Thunderbolt 4?

Also, would someone offer an opinion as to why a Thunderbolt 4 peripheral would have a 770 MB/s link speed test result?

In addition, I believe that the Thunderbolt 4 (Host) controller would be the Intel JHL8540 or the Intel JHL8340 controller.

If this is correct, should the Intel JHL8540 and the Intel JHL8340 controllers have the same specifications, as published for the Intel JHL8440?

I ask this because the information provided by the Intel JHL8540 and Intel JHL8340 Thunderbolt 4 Controller Product Specifications, at the following links are not the same as the Intel JHL8440.

https://ark.intel.com/content/www/us/en/ark/products/193684/intel-jhl8540-thunderbolt-4-controller.html

and

https://ark.intel.com/content/www/us/en/ark/products/193688/intel-jhl8340-thunderbolt-4-controller.html

Here is what is provided by the Intel JHL8540 and Intel JHL8340 Thunderbolt 4 Controller Product Specifications.

I/O Specifications

PCI Express Configurations ‡ x4 Gen3
capabilities: ACS, FPB, PTM, P2P, 128b payload
Display Port 2 DP Sink, 1 DP SRC, DP1.4a tunnel/re-drive x1/x2/x4 1.62/2.7/5.4/8.1

Thank you, in advance, for your time and assistance with addressing my questions.

[Jose_Intel]

Hello @fp5849

Thank you for posting on the Intel️® communities.

We understand you have opened multiple community support cases with us. Therefore, will continue our support through that channel now. We will be closing this community case. Please, keep in mind that this thread will no longer be monitored by Intel.

Thanks for your understanding.

Best regards,

Jose B.

Intel Customer Support Technician