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jason.siegel

macrumors 6502
Original poster
Jun 15, 2011
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Can a USB-C 3.2 Gen 2 drive be used with a MacBook Pro M1 Pro? And if yes, do the speeds just max out at the Macbook limit?
 
The MacBook should support to up to 40Gbps speed (both thunderbolt 4 tech and USB4)

There were some compatibility issues with the M1 with some of the external SSDs (mostly with it not connecting in full 10gbps link speed but only 5gbps.)

We should see later on..
 
M1 USB problems are discussed at https://forums.macrumors.com/thread...ally-10gb-s-also-definitely-not-usb4.2269777/

I guess you should be able to get 3 GB/s by connecting one USB 10 Gbps drive per Thunderbolt port.
Maybe 5 GB/s with multiple Thunderbolt docks: 22 Gbps per Alpine Ridge dock, 10 Gbps per Titan Ridge dock or Goshen Ridge dock (if you disable USB4 tunnelling).

ATTO Disk Benchmark.app can test read/write to multiple drives without having to create a RAID 0.

We need benchmarks of various setups to know the limits and to answer some questions. For example, is it possible to get more than 25 Gbps of PCIe data per Thunderbolt port? We know that discrete Thunderbolt controllers like Titan Ridge or Alpine ridge were limited to ≈23 Gbps even when using two separate Thunderbolt ports. Integrated Thunderbolt controllers such as Ice Lake can do ≈38 Gbps from two or more ports but I don't think anyone has tested multiple devices connected to a single port. M1 Macs fall into the integrated Thunderbolt controller category but I haven't seen testing of multiple devices with multiple ports or single port.
 
Anything new on that topic? Would really like to purchase the SanDisk ExtremePro 2TB with 2000MB/sec for my new MacbookPro.
 
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Anything new on that topic? Would really like to purchase the SanDisk ExtremePro 2TB with 2000MB/sec for my new MacbookPro.
You're asking if the new M1 Macs supports USB 3.2 gen 2x2? I don't think so.
Next question is, does Monterey have drivers for USB 3.2 gen 2x2 USB cards. I don't think so.
I don't have an M1 Mac but I do have a USB 3.2 gen 2x2 USB card. I'll do some testing later.
 
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How did testing this go?
I don't have an M1 Mac to test Apple Silicon drivers.
I can connect 10 Gbps devices to the USB 3.2 gen 2x2 card and they'll work (the PCIe card is connected via Thunderbolt to a Mac mini 2018).
If I connect a 20 Gbps device, it does not appear in macOS.
I think a simple kext patch should make 20 Gbps possible but I haven't looked into it. An alternative would be to use the GenericUSBXHCI.kext (will require some modifications to the code).
 
The computers :
iMac 24 M1 2020
MacBook Pro M1 Max 2021

The SSD :
WD My Passport (USB3.2)
 

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I made a relevant post in another thread. This Amazon review summarised the M1 USB compatibility issues nicely.

Can a USB-C 3.2 Gen 2 drive be used with a MacBook Pro M1 Pro? And if yes, do the speeds just max out at the Macbook limit?
I think the answer is yes, and it will max out at around 1,000MB/s.

Anything new on that topic? Would really like to purchase the SanDisk ExtremePro 2TB with 2000MB/sec for my new MacbookPro.
I have been looking at this SSD but unfortunately I think it will max out at 1,000MB/s on M1/M1 Pro/M1 Max.
 
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Anything new on that topic? Would really like to purchase the SanDisk ExtremePro 2TB with 2000MB/sec for my new MacbookPro.
Just had this exact drive arrive and can confirm it only connects at 10gb/sec, topping out at about 900MB/s.

I’m a bit puzzled because the Apple site says the 16MBP has both TB4(40gb/s), and usb4(40gb/s)…which should be able to hi the advertised SSD speed of 2000 MB/s.

Feel a bit misled or confused. Maybe both at this point.
 

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Just had this exact drive arrive and can confirm it only connects at 10gb/sec, topping out at about 900MB/s.

I’m a bit puzzled because the Apple site says the 16MBP has both TB4(40gb/s), and usb4(40gb/s)…which should be able to hi the advertised SSD speed of 2000 MB/s.

Feel a bit misled or confused. Maybe both at this point.
I am repeating myself, but this Amazon review is a helpful summary of the USB specs. USB 3.2 Gen 2x2 is optional under the USB4 standard, and cannot coexist alongside Intel Thunderbolt 3 controller. I’m glad I did some research before making a purchase, but it’s been very confusing.
 
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I am repeating myself, but this Amazon review is a helpful summary of the USB specs. USB 3.2 Gen 2x2 is optional under the USB4 standard, and cannot coexist alongside Intel Thunderbolt 3 controller. I’m glad I did some research before making a purchase, but it’s been very confusing.
I’m with you to the point where the Apple site states 40gb/s usb4 ports x3.


For giggles I looked the usb 4 spec up. USB4 40 Gbit/s Transport does state optional, but since the Apple site does say 40gb/s, I don’t see why the setup cannot hit advertised speeds.

Regardless, SSD will go back and I’ll get the gen1. Feels misleading by Apple. I will say the state of USB4 standards is terrible, it should not be this complicated.
 

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For giggles I looked the usb 4 spec up. USB4 40 Gbit/s Transport does state optional, but since the Apple site does say 40gb/s, I don’t see why the setup cannot hit advertised speeds.
[emphasis mine]

Yes, that is definitely true, I was initially of the impression that if it can go 40Gb/s, why not 20Gb/s; until I went digging.
 
USB4 40 Gbit/s Transport does state optional, but since the Apple site does say 40gb/s, I don’t see why the setup cannot hit advertised speeds.

USB4 supports several signal modes:
-------------
USB 1.1: 1.5 Mb/s
USB 1.1: 12 Mb/s
USB 2.0: 480 Mb/s
========
USB 3.0: 5 Gbps
USB 3.1 gen 2: 10 Gbps
USB 3.2 gen 2x2: 20 Gbps
-------------
USB4 gen 2: 20 Gbps
USB4 gen 3: 40 Gbps
-------------
Thunderbolt: 20.625 Gbps
Thunderbolt: 41.25 Gbps
-------------

I've grouped them by similarity. The 20 Gbps USB 3.2 mode is not similar to the USB4 or Thunderbolt modes and is optional for USB4 and Thunderbolt ports.
Above the ======== are modes that use the high speed D+ D- lines (2 pins, 1 differential pair, for send and receive).
Below the ======== are modes that use the super speed Tx Rx lines (4 pins, 2 differential pairs, one pair for each direction).
Starting with the 3.2 mode, are those that use two lanes in each direction (8 pins, 4 differential pairs, two pairs for each direction) and therefore require a USB-C connection (not USB-A). I did not list the single lane USB4 and Thunderbolt modes which usually only happen if you use a bad cable.

USB 3.x are usually provided by XHCI controllers. This is usually a separate controller from the Thunderbolt or USB4 controller. A Thunderbolt or USB4 chip may contain an XHCI controller. The XHCI controller in known USB4 and Thunderbolt implementations does not include USB 3.2 gen 2x2 support.
 
So what I'm seeing is that the new M1 MBPs support USB4 (Gen 3×2- 40 Gbps). By USB4 standards, it supports backwards compatibility of USB 3.2 (10Gbps), but not USB 3.2 (Gen 2x2-20Gbps). I don't honestly know why 3.2 2x2 exists and is not a requirement for USB 4.

That is incredibly confusing standards implementation (USB-IF) & unclear marketing (Apple).



To hit above 900MB/s, consumers should look for TB3/TB4/USB4 on the label. $$$ that most don't want to spend after $4k on a laptop haha.

Is what it is.
 
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So I picked up a Samsung T7. It's USB-C 3.2 and suppose to give me 1000mbps read/write

I tried it on my 16" 2019 MacBook Pro, 14" base model MacBook Pro, and my gaming pc. None of them hit those speeds.
I can't figure it out
 
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So what I'm seeing is that the new M1 MBPs support USB4 (Gen 3×2- 40 Gbps). By USB4 standards, it supports backwards compatibility of USB 3.2 (10Gbps), but not USB 3.2 (Gen 2x2-20Gbps). I don't honestly know why 3.2 2x2 exists and is not a requirement for USB 4.

That is incredibly confusing standards implementation (USB-IF) & unclear marketing (Apple).

There is a much larger tech world beyond our relatively tiny Apple bubble. Just because something doesn't play well with Apple doesn't mean it doesn't work exactly as intended with far more technology devices.

But I certainly agree that "standards" should be standards and not require consumers to "just buy it and test" to see if something will work as marketed.
 
From reply 18 above:
"...I picked up a Samsung T7. It's USB-C 3.2 and suppose to give me 1000mbps read/write
I tried it on my 16" 2019 MacBook Pro, 14" base model MacBook Pro, and my gaming pc. None of them hit those speeds."


You won't get 1000MBps. That's a "theoretical limit" and I doubt that anyone ever sees it.
You MIGHT get upwards of 900MBps.
You're more likely to get reads of 800+MBps and writes in the 600-700 range.
 
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From reply 18 above:
"...I picked up a Samsung T7. It's USB-C 3.2 and suppose to give me 1000mbps read/write
I tried it on my 16" 2019 MacBook Pro, 14" base model MacBook Pro, and my gaming pc. None of them hit those speeds."


You won't get 1000MBps. That's a "theoretical limit" and I doubt that anyone ever sees it.
You MIGHT get upwards of 900MBps.
You're more likely to get reads of 800+MBps and writes in the 600-700 range.
Yeah I showed the results I got in the video.

I'm just bummed out that my 2 year old intel MacBook got better speeds than my new 14".
 
There is a much larger tech world beyond our relatively tiny Apple bubble. Just because something doesn't play well with Apple doesn't mean it doesn't work exactly as intended with far more technology devices.

But I certainly agree that "standards" should be standards and not require consumers to "just buy it and test" to see if something will work as marketed.
Yep, I hear ya. Its not that it isn't playing well, its working as the standard implies...but the standard is too complex (USB shouldn't be), and the vendor marketing is made to sell.

Will settle for 900MB/s.
 
Yeah I showed the results I got in the video.

I'm just bummed out that my 2 year old intel MacBook got better speeds than my new 14".
You would get better numbers (1060 MB/s) with an NVMe in a USB NVMe enclosure.
Also, AmorphousDiskMark.app gives higher benchmark numbers.

As for USB 3.2 Gen 2x2, you could get an ASM3242 and install a third party driver and get 20 Gbps. The driver is old but open source and needs updating.
https://forums.macrumors.com/threads/usb-3-x-pcie-cards-for-classic-mac-pro.1501482/
 
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