USB-C v. USB 3.x v. Thunderbolt 2,3,4,5

[ufgatorvet]

Noob question here, please forgive my noob-ness.

To my understanding (youtube research) ...

Known variables:
1. The new MacBook Air M4 has 2 TB4 ports.
2. I have an Apple SD card reader as well as a "SanDisk 4TB Extreme Portable SSD - Up to 1050MB/s, USB-C, USB 3.2 Gen 2" external drive.

Hypothesis: Am I correct that both of these peripherals will work with the MBA M4 due to TB backward compatibility? Am I also correct that TB4 ports can work with any USC-C 3.2 devices, but TB4 devices WILL NOT work with standard USB-C 3.2 ports?

Thanks for the response and minimal eye-rolling 😂

 

[ufgatorvet]

So sorry, posted in wrong forum. Noob move

 

[joevt]

So sorry, posted in wrong forum. Noob move

Somebody might move it.

Hypothesis: Am I correct that both of these peripherals will work with the MBA M4 due to TB backward compatibility?

Yes.

Am I also correct that TB4 ports can work with any USC-C 3.2 devices,

Yes. If it's a device that macOS has a driver for (standard USB devices, some non-standard USB devices).

but TB4 devices WILL NOT work with standard USB-C 3.2 ports?

Some Thunderbolt 4 devices can be used with standard USB-C ports. Check the specs of the Thunderbolt 4 device.

 

[ufgatorvet]

I appreciate your reply! Thank you!

 

[Anonymous Freak]

Short form:

Any Mac port that is "Thunderbolt 3", "Thunderbolt 4", or "Thunderbolt 5" (USB Type C style port with the little thunderbolt logo) will function with any Thunderbolt or USB device, although some pairings of device/Mac may not run at full speed, and there may be some "number of device" limitations. (For example, some early Apple Silicon Macs only supported one single external display via Thunderbolt, so while a Thunderbolt Display or USB-C display would work on any of the Thunderbolt ports, only one single display would work at a time.)

Any Mac port that is a "USB Type C" style port that *ISN'T* labeled with the little thunderbolt (front ports on the non-ULTRA Mac Studios, front ports on the latest-generation Mac mini,) only supports USB data, not Thunderbolt devices, not display output.

All Apple Silicon Macs support up to 10 Gbps on "non-Thunderbolt" USB devices on all USB or Thunderbolt ports.
Thunderbolt ports support Thunderbolt-specific devices up to 40 Gbps or up to 120 Gbps depending on model.

---

Long form:

USB 3+ is the absolute most confusing mess of a "standard" that has ever existed.

Wait until you hear about "USB 3.2 Gen 2 2x2"…

It's the USB standard that supports 20Gbps transfer.

Only it isn't automatic that later versions of USB support 20Gbps.

USB4, Thunderbolt 4, Thunderbolt 5 on Apple Silicon Macs don't support the "non-Thunderbolt" 20Gbps speed. To support faster than 10Gbps, the device must be a "Thunderbolt" device, not a USB device.

*SIGH*

 

[joevt]

To support faster than 10Gbps, the device must be a "Thunderbolt" device, not a USB device.

A Thunderbolt device could support "USB gen 2x2" if it contains a "USB gen 2x2" controller.

Thunderbolt 5 docks and hubs have such a USB controller built into their Thunderbolt controller but it gets bypassed by Apple Silicon Macs which use tunnelled USB from the Mac's USB 3.2 gen 2x1 controller.

USB tunnelling can be disabled by placing a Thunderbolt 3 device between the Apple Silicon Mac and the Thunderbolt 5 hub/dock.

Alternatively, a Thunderbolt 3 PCIe expansion chassis can be used to host a PCIe USB gen 2x2 XHCI controller card.

I wouldn't call USB4 a later version of USB 3.2. They're quite different. They are different specs. USB4 does include support for USB 3.2. The USB4 spec does not describe all of USB 3.2 - you need the USB 3.2 spec for that.

 

[theluggage]

I wouldn't call USB4 a later version of USB 3.2. They're quite different. They are different specs. USB4 does include support for USB 3.2. The USB4 spec does not describe all of USB 3.2 - you need the USB 3.2 spec for that.

Yup.
USB4 is the (more open) successor to Thunderbolt 3, using the same underlying 20Gbps tech - and has much the same relationship to USB 2/3/3.1/3.2 that Thunderbolt 3 did. Like TB3, it depends on USB 3.2 and other USB standards for backwards-compatibility & power delivery, but doesn't define them. C.f. TB3 it adds support for hubs with multiple downstream TB/USB4 ports and USB 3.2 tunneling.

USB4 leaves a lot of stuff - like some legacy TB1/2/3 features and multi-display support optional. Starting with TB4, Thunderbolt is effectively just an Intel branding and certification scheme for USB4 devices with a lot of the "optional" stuff made compulsory. All Apple Silicon Macs have had USB4 ports - the only reason that some MacBooks label them as "TB3/USB4" rather than TB4 is that those machines don't support at least two external displays via TB/USB4 - which is a requirement of TB4 certification.

USB4v2 adds 80Gbps speeds - TB5 is the Intel-certified version of that.

It's ridiculously confusing to punters - esp. with the USB-IFs inconsistent way of numbering standards, re-naming existing standards (USB 3.0 -> USB 3.1 gen1 etc.) and insisting on slapping the "USB" tag over everything. I know why they do it - brand recognition - but it would have been so much clearer if they'd called USB-C - oh, I dunno, "UniPlug" and USB4 "OpenBolt" (feel free to invent better names). Then there's the "latest USB standard doesn't actually require support for its major new feature" fun - which is where Thunderbolt has really come in as "The USB-C port where you can actually make some reasonable assumptions about what it supports!".

It's the USB standard that supports 20Gbps transfer.

More expansively, it's the standard that supports using two USB 3.1 channels in tandem to get a 10Gbps (2 x 5G) or 20Gbps (2 x 10G) connection. C.f. TB3 which goes up to 20Gbps per channel and can join two to get 40Gbps. I don't think its any great loss that Apple don't support it - it always looked like a dead end with Thunderbolt offering true 20Gbps, USB 3.1 still at the "good enough for most folks" stage and large chunks of the PC market still pretty wedded to USB-A ports (which can happily go up to 10G, but not 20).

 

[joevt]

More expansively, it's the standard that supports using two USB 3.1 channels in tandem to get a 10Gbps (2 x 5G) or 20Gbps (2 x 10G) connection. C.f. TB3 which goes up to 20Gbps per channel and can join two to get 40Gbps. I don't think its any great loss that Apple don't support it - it always looked like a dead end with Thunderbolt offering true 20Gbps, USB 3.1 still at the "good enough for most folks" stage and large chunks of the PC market still pretty wedded to USB-A ports (which can happily go up to 10G, but not 20).

Apple doesn't have any USB 3.2 gen 2x2 ports but does support such USB controllers since Sonoma so they can be added via PCIe card or Thunderbolt 5 dock/hub.

 

[Anonymous Freak]

I don't think its any great loss that Apple don't support it - it always looked like a dead end with Thunderbolt offering true 20Gbps, USB 3.1 still at the "good enough for most folks" stage and large chunks of the PC market still pretty wedded to USB-A ports (which can happily go up to 10G, but not 20).

For me, the only annoying part is that I do have a SanDisk USB 3.2 Gen 2 2x2 20Gbps external SSD that *IS* capable of >10Gbps; but 10Gbps is the cap on my Macs. It was quite a bit cheaper than a true Thunderbolt SSD of same capacity, and when M1 Macs came out, I saw "USB4" and naively assumed they would support 20Gbps USB 3.2.

 

[Anonymous Freak]

A Thunderbolt device could support "USB gen 2x2" if it contains a "USB gen 2x2" controller.

I was keeping it simple for my simple section, referring only to the ports on Macs.

Back in the day, I used a Thunderbolt 1 dock to add USB 3 to my iMac, it's definitely possible to use TB to add capabilities; I didn't want to go into that level of detail.

 

[ufgatorvet]

Everything after the second "Yes" in joevt's response post #3, well, you lost me. 😂

I got the answer I needed, you kids take it from here and go on and have fun!

After all, I can't even post in the correct forum, you can't expect me to spell UBS!!

 

[theluggage]

A Thunderbolt device could support "USB gen 2x2" if it contains a "USB gen 2x2" controller.

Only if the host OS supports USB gen 2x2 or the device comes with a driver you can install - either the USB is tunnelled from the host controller "USB4 style" or the USB controller appears on the PCIe bus "Thunderbolt 1/2/3 style" - in which case the host OS needs to load a driver for the new controller.

Not impossible, but do you have any examples of devices that work?

Meanwhile, I see we now have to cope with descriptions like "Interface: USB4 Gen 3x2" (Not to be confused with USB3.2 Gen 2x2) - it's not even necessarily wrong, just needlessly confusing because the USB-IF insist on using "USB + version number" inconsistently to refer to both specific protocols and complete protocol stacks... even before that gets "interpreted" my device makers.

 

[joevt]

Not impossible, but do you have any examples of devices that work?

macOS Sonoma and Sequoia have support for USB 3.2 gen 2x2. With my Intel Mac mini (2018), I used a Sonnet Echo Express III-D (Thunderbolt 3 Edition) with an ASMedia ASM3242 USB 3.2 gen 2x2 PCIe card. I connect a USB 3.2 gen 2x2 NVMe enclosure and got 1869 MB/s read.
https://www.startech.com/en-ca/cards-adapters/pexusb321c

I don't think I've seen anyone test USB 3.2 gen 2x2 with an Apple Silicon Mac either using a Thunderbolt PCIe Expansion Chassis like I did, or a Thunderbolt 5 dock/hub with a Thunderbolt 3 device between the Apple Silicon Mac and the Thunderbolt 5 device.

Meanwhile, I see we now have to cope with descriptions like "Interface: USB4 Gen 3x2" (Not to be confused with USB3.2 Gen 2x2) - it's not even necessarily wrong, just needlessly confusing because the USB-IF insist on using "USB + version number" inconsistently to refer to both specific protocols and complete protocol stacks... even before that gets "interpreted" my device makers.

gen 3 in relation to USB 3.x and USB4 refers to 20 Gbps. 2 lanes of that is 40 Gbps = USB4.
Actually, gen 3 has no relation to USB 3.x since USB 3.x only goes up to gen 2 (10 Gbps per lane similar to Thunderbolt 1/2 or Thunderbolt 3/4 slow mode).
Then there's USB4v2 gen 4 symmetric (80 Gbps), and asymmetric (120/40) or reverse asymmetric (40/120).

 

[Adora]

@joevt

Thanks for all that information.

I am always confused about those USB-C ports without Thunderbolt. It looks like they only support USB 3.1, because the Bus version is 3.1 but it shows 3.2 in the device tree. For the speed it doesn't matter anyway. I just wonder if the advantages of 3.2 can even be used. I don't know any in my use case for now. Especially with only USB 2 devices connected at the moment.

I have two 3.2 Gen 2 Hubs where all ports support 10Gb/s, one is connected to the other and the first one is shown as USB 3 Gen 2 instead of USB 3.2 Gen 2. Very strange.
They are the same brand, the one directly connected to the Mac has two USB-A and two USB-C ports and the other one four USB-C ports.
All USB-A ports on both of them are orange inside. Does the color stand for 3.2 Gen 2? Or something else?

There is also my secondary TimeMachine drive an SSD (CT4000...) connected to the second front port.

Both ports seem to use the same bus, what is even more confusing because it's 5 busses and 5 ports alltogether with the three TB5/USB4 ports. At the moment there is only one TB3 SSD connected and the other two ports are free.


It looks like that on my M4 Pro Mini:

This looks so confusing. The Sound Blaster is the only thing connected to the second USB-Hub what is hanging on the first Hub, but look like it's connected to the first Hub and the second one is empty. The SSD isn't on any Hub but it looks like that.



The empty busses only show:

Host Controller Driver: AppleUSBXHCITR


Except the last one, that is showing:

Host Controller Driver: AppleUSBXHCITR
PCI Device ID: 0x15f0
PCI Revision ID: 0x0006
PCI Vendor ID: 0x8086

 

[joevt]

I am always confused about those USB-C ports without Thunderbolt. It looks like they only support USB 3.1, because the Bus version is 3.1 but it shows 3.2 in the device tree. For the speed it doesn't matter anyway. I just wonder if the advantages of 3.2 can even be used. I don't know any in my use case for now. Especially with only USB 2 devices connected at the moment.

You can ignore the USB 3.1/USB 3.2 difference.
USB 3.0, USB 3.1 gen 1 and USB 3.2 gen 1x1 are all the same (5 Gbps)
USB 3.1 gen 2 and USB 3.2 gen 2x1 are all the same (10 Gbps)
USB 3.2 gen 1x2 (10 Gbps) and USB 3.2 gen 2x2 (20 Gbps) are new to USB 3.2 but Apple Macs do not come with controllers that can do x2.

USB 2.0 is totally separate from USB 3.x. USB 2.0 uses different wires so it doesn't interfere with USB 3.x.

I have two 3.2 Gen 2 Hubs where all ports support 10Gb/s, one is connected to the other and the first one is shown as USB 3 Gen 2 instead of USB 3.2 Gen 2. Very strange.
They are the same brand, the one directly connected to the Mac has two USB-A and two USB-C ports and the other one four USB-C ports.

Some USB hubs have name strings in their device info which System Profiler.app will display. Ignore the name and look at the connection speed info.

All USB-A ports on both of them are orange inside. Does the color stand for 3.2 Gen 2? Or something else?

Some manufactures follow a USB color convention. Some (Apple) do not.
https://www.storagereview.com/news/what-is-usb-c-background-and-overview

Both ports seem to use the same bus, what is even more confusing because it's 5 busses and 5 ports alltogether with the three TB5/USB4 ports. At the moment there is only one TB3 SSD connected and the other two ports are free.

A bus has one or more ports.
Apple Silicon Macs have one Thunderbolt port per Thunderbolt bus (controller). I think they also have one USB port per USB bus (controller) or two USB ports since there is one port for USB 3.x traffic and another port for USB 2.0 traffic.

It looks like that on my M4 Pro Mini:

View attachment 2508962

This looks so confusing. The Sound Blaster is the only thing connected to the second USB-Hub what is hanging on the first Hub, but look like it's connected to the first Hub and the second one is empty. The SSD isn't on any Hub but it looks like that.

A USB hub can be connected to a port of anther USB hub. It's a tree structure with the Mac as the trunk.

The SSD is a USB device. It is connected to a hub which is connected to a USB bus (controller).
The hub may be an external hub or it might be inside the Mac or inside the SSD.

The empty busses only show:

Host Controller Driver: AppleUSBXHCITR

TR is TitanRidge which is an Intel Thunderbolt 3 controller.
XHCI is a USB controller. A Thunderbolt controller may contain a USB controller.
I suppose Apple could use this driver for its USB controllers?

Except the last one, that is showing:

Host Controller Driver: AppleUSBXHCITR
PCI Device ID: 0x15f0
PCI Revision ID: 0x0006
PCI Vendor ID: 0x8086

8086:15f0 is https://admin.pci-ids.ucw.cz/read/PC/8086/15f0
Maybe this one is inside the TB3 SSD?

The output from the ioreg command might be more informative because it includes USB ports that have nothing connected to them.
You can find IORegistryExplorer.app from Apple developer tools. It has a nice UI to view the I/O registry. Then you can look for the USB controllers and hubs and ports.
You can connect/disconnect a USB or Thunderbolt device and the nodes in the IO Registry will appear as green (newly connected) or red (newly disconnected).

 

[Melbourne Park]

Where can I find a thread about which drive to attach to my Macbook M4 Max (whose drive is not big enough for what I'll soon need)?

It seems to me either a Thunderbolt 3 drive or a Thunderbolt 5 drive is the only way to get assured performance. And then, what to buy?

I've also wondered about putting in flash memory into an external T-5 casing, which seems a cheap and flexible way.

On looking at drives, a Sandisk 4TB Extreme PRO USB4 Portable SSD costs a bit over $US400. It promises on a Mac using T-3 I think, 3800 ... and there is a Thunderbolt 3 version. On reading reviews by Mac users, some have reported issues with the drives.

Samsung T-9 is fine for PCs, but the T-9 on a Mac is not faster than a T-7 drive, around 1000. Cost for 4TB is around $US300. A T-7 is 10% less, but just as good on a Mac. Who wants just 1000 though?

Oyen Thunderbolt 4 drives - Lots of good user reviews. Around $US430 for 4 TB, and $US270 for 2 TB.

Sabrent has a Thunderbolt-3 2TB drive for less - around $US250

Sonnet has a (costly) Thunderbolt 5 Dock which includes a 4 TB SSD drive, and it has 4 T-5 Ports and also 3 USB-A 3.2 ports (at 1000 speeds for the USBs) $US750
2TB version of the same is $US550

When available, La Cie Rugged Pro 5 Thunderbolt 5 drives:
2TB: $US350
4TB: $US550
(their Pro 3 - Thunderbolt 3 - 2TB around $US275
Pro 3 - Thunderbolt 3 - 4TB around $US465
These La Cie drives though are often out of stock. Ruggedised sounds useful, but I imagine cooling would be more difficult due to their rugged casings.

OWC Envoy Thunderbolt 5 2TB $US380
OWC Envoy Thunderbolt 5 4TB $US550
OWC's Thunderbolt 3 drives seem less than 10% lower in cost than the T-5 drives.
OWC also has a Thunderbolt 5 powered Hub, with 3 Thunderbolt 5 USB-C ports (and an A port) for $US170.
If this OWC T-5 hub provided USB 3.3 2000 speeds via its USB type C ports (these drives only run at 1000 on Mac) then one could buy this drive and buy much lower cost USB-C 3.3 ie 2000 speed drives. Not sure if that is a reasonable option or not.