I have been told that the Intel TB4 Controller will only support One (1) Lane of PCIe data.
Is this correct?
Is the TB 4 data (32Gb/s: 40Gb/s less ~8Gb/s for DisplayPort) and PCIe data, over a TB 4 link, the same thing?
Mac mini, macOS 13.6
Double Double
Thunderbolt 4 raises and standardizes the minimum host system requirements. It offers 40Gb/s, two 4K displays or one 8K display, and PCIe data at 32Gb/s on all ports, effectively doubling the minimum expectations of Thunderbolt 3.
For example, the MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports) has two 40Gb/s ports on the left and two 20Gb/s ports on the right1. That means specific ports would throttle PCIe speeds to 16Gb/s and only support one 4K display. With Thunderbolt 4, this will not be allowed – all four ports will be required to be 40Gb/s.
https://eshop.macsales.com/blog/63715-intel-introduces-thunderbolt-4-what-is-it-and-does-it-matter/
Double Double
Thunderbolt 4 raises and standardizes the minimum host system requirements. It offers 40Gb/s, two 4K displays or one 8K display, and PCIe data at 32Gb/s on all ports, effectively doubling the minimum expectations of Thunderbolt 3.
For example, the MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports) has two 40Gb/s ports on the left and two 20Gb/s ports on the right1. That means specific ports would throttle PCIe speeds to 16Gb/s and only support one 4K display. With Thunderbolt 4, this will not be allowed – all four ports will be required to be 40Gb/s.
https://eshop.macsales.com/blog/63715-intel-introduces-thunderbolt-4-what-is-it-and-does-it-matter/
Any help, orv just more confusion???
Thunderbolt 3's bandwidth sharing mechanism between video and data also put in some dampeners – even in the absence of tunneling DisplayPort streams, 18 Gbps of bandwidth was always reserved for video traffic, and only 22 Gbps available for actual data transfer. Thunderbolt 4 apparently fixes that with up to 32 Gbps of data traffic (full PCIe 3.0 x4 bandwidth) available, allowing devices such as Thunderbolt 4 SSDs to provide 3GBps+ speeds.
I think Ganesh got it wrong in his report. For one thing, I believe Thunderbolt 4 has not fixed the PCIe limitation, but I generally trust AnandTech's QC so am hesitant. However, I saw some posts here that suggest the JHL7440 chip somehow manages to have up to 24 Gbps Device-to-Host bandwidth (assuming the reading is accurate), which should be impossible if the 22 Gbps is "hardcoded".
https://egpu.io/forums/thunderbolt-enclosures/technical-questions-on-tb3-pcie-tunnelling-bandwidth/
I almost went for the Ministack, but since I only have TB3 on my 2019 iMac, I wnt with the OWC 14-Port Thunderbolt Dock, which came today, and the pass through TB3 port is slower than the computers TB3 port...
2.0TB OWC Envoy Pro FX connected directly to iMac...
2.0TB OWC Envoy Pro FX connected to the pass through TB3 port on the OWC 14-Port Thunderbolt Dock...
The reason for my question about "TB4 Data" vs "PCIe Data" is more nuanced and needs further explanation.
OWC (MacSales.com) offers a product called the miniStack STX.
The miniStack STX has:
(1) bay supporting: (1) 3.5-inch SATA 6.0 SSD/HDD drive -or- (1) 2.5-inch SATA 6.0 SSD/HDD drive
(1) bay supporting: NVMe M.2 SSDs with 2280 form factor and "M Key" connector type.
(1) Host Port - Thunderbolt 4 (USB-C) at up to 40 Gb/s (5000 MB/s)
(3) Device Ports - Thunderbolt 4 (USB-C) Ports at up to 40 Gb/s (5000 MB/s)
With 770MB/s of "real-world" data transfer speed.
My question to OWC was why the link speed is only 770MB/s ("real-world"), when the miniStack STX uses:
and a ...
Note: It is my understanding that a more realistic speed, per port, would be up to ~22Gb/s (~2750MB/s) after accounting for the data reserved for DisplayPort and USB data.
The answer OWC provided me was:
"The Intel Thunderbolt 4 Controller used (in the miniStack STX) is limited to One (1) PCIe lane, unlike the previous Thunderbolt 3 controllers".
So, I am trying to find out if this is correct.
One assumption I am making is that the TB4 Controller being used is the Intel JHL8440 (or something similar).
The Intel JHL8440 is the only TB4 Controller I found with the specifications of:
The JHL8440 specification also stated it has the following native interfaces:
So, I may be incorrect as to the specs of the TB4 Controller the miniStack STX is using.
But, assuming this is the correct (similar) TB4 Controller:
It is my understanding that "PCIe 3.0 x1" equals one (1) Lane of PCIe data at only ~1 GB/s.
If this is the case, the miniStack STX's link speed of 770MB/s makes sense.
But, how can the the TB4 Controller "also" support data transfer of "PCIe (32G)"?
All of the references I have read appear, to me at least, to the discuss TB4 data and PCIe data interchangeably.
So, how can a device which does not provide 32Gb/s of PCIe data, to the Host, be specificity as TB4?
Yet the same device is stated to provide (4) Thunderbolt 4 (USB-C) ports at up to 40 Gb/s (5000 MB/s), per port.
How is this possible, if the TB4 link between the Host and the miniStack STX is only stated to be 770GB/s?
What am I misunderstanding?
So this leads me back to the original question:
"Is TB4 data and PCIe data over a TB4 link the same thing?"
Any assistance answering this (these) question(s), would be appreciated.
FrankPerry wrote:
Yet the same device is stated to provide (4) Thunderbolt 4 (USB-C) ports at up to 40 Gb/s (5000 MB/s), per port.
Four USB-C (Thunderbolt) ports – one of which is an upstream port, three of which are downstream ports.
Clearly the single link between the MiniStack STX and the computer is not going to be able to support full-speed data transfers between the computer, and devices on all three downstream ports, at the same time. Breaking the Thunderbolt chain into three chains is about convenience, not about violating the laws of physics …
Is that a way to verify that a (the) TB4 Controller only supports One (1) PCIe Lane vs TB3 supporting four (4) PCIe Lanes, as I was informed?
How can the chip-set be TB4, if the link to the Host is only 770MB?s?
Could the vendor (OWC) be changing something, to save money, to make the NVMe PCIe M.2 slot only support One (1) PCIe Lane.
How can the Intel's specs for the TB4 chip-set be spec'd as both have only PCIe 3.0 x1 and PCIe 32Gb/s?
Do you know if the Intel spec's use of the term "native interface" in reference to "PCIe 3.0 x1" references something different from the TB4 requirement to support a minimum of 32Gb/s?
Thanks for your time.
Hi BDAqua,
Also, I have noticed the other OWC TB3 Drive Enclosure have much higher speed than the TB4 miniStack STX.
Which is what i see in the test results you provided.
Again, OWC is telling me that the relatively low speed of the TB4 miniStack STX vs the their other OWC TB3 products is because of the TB4 Controller being used.
Please see my reply to Servant of Cats.
Thanks
Is TB 4 data and PCIe data over a TB 4 link the same thing?
