The issue is not a cable thing. I have experienced the same behaviour on both a 2020 intel MBA and a 2021 M1 Pro; a 10GB/s rated Samsung T5 SSD only connects to either Mac at 5GB/s, despite being rated for 10GB/s. The same SSD (and cables) connects to Linux & Windows boxen at 10GB/s.

Equally, a Crucial X8 SSD rated for the same 10GB/s connects to both Macs at its rated speed.

This behavious has persisted across OS updates since Big Sur.

My current thinking is that there's some undocumented quirks in place in MacOS that scales speeds down with certain USB controllers.

Sounds pretty clearly like Apple thinks certain devices are non-standards compliant. And just because it works at full speed on Linux & Windows doesn't mean it's standards compliant.

Alternatively Apple is not standards compliant. Or it could just be a bug in their driver or controller. Not sure why it makes more sense to assume Apple is doing it right and everyone else wrong.

Why bother reading the article when you can just slam out hot takes?

> Cables used included a certified Thunderbolt 4 model, and the USB-C (data) cables provided with the cases. Again, each was verified by establishing SuperSpeed+ 10 Gb/s connections to an Intel Mac.

Because we all know unnamed brand / model “certified” cables with drives that are also unnamed brand / model could surely not be the problem?

Edit: I did read the entire article. Like others have said here, it doesn’t match with my experience. But because nothing is clearly specified as to what’s used, the article is useless because nobody can compare to see if their setup is the same or different.

Just because it works on an Intel Mac does not mean the cable isn’t the issue! Happy to demonstrate in a live video along with oscilloscope readings to prove it is in fact the cable to blame.

I would like to see this. Mostly to see what kind of an absolute beast of an oscilloscope can keep up with the data rate.

Also I don't understand why people are disagreeing with you. If a cable is not within spec it's absolutely possible for it to work in one circumstance because for example the port is more lenient and completely fail with a port that is more strict.

> Mostly to see what kind of an absolute beast of an oscilloscope can keep up with the data rate.

You can prove a cable faulty without being able to fully observe/measure the entire frequency range at once.

> Also I don't understand why people are disagreeing with you. If a cable is not within spec it absolutely possible for it to work in one circumstance because for example the port is more lenient and completely fail with a port that is more strict.

I’m kinda baffled too. I thought this was common knowledge among the folks on HN, but maybe not?

What's your theory as to why the cable would be at fault, despite working perfectly well in a different machine?

Seems like the simplest counterpoint would be to demonstrate a M1 mac transmitting at the full data rate using a different cable.

> Seems like the simplest counterpoint would be to demonstrate a M1 mac transmitting at the full data rate using a different cable.

Which I’d be happy to do assuming I knew the exact specs (brand/model) of the drives OP was using.

If you’d like me to demonstrate that MacOS on Apple Silicon correctly supports USB 3.2 gen 2 devices at 10Gb/s using multiple brands of drives/models, happy to do as well.

I really like (careful, sarcasm) that about USB-C and HDMI. You have a port, you have a cable. But if you're not a Syadmin you have no idea why it does not work as you think it should.

I can't understand why they did not put some kind of capability mark for cables/ports into the spec.

> I can't understand why they did not put some kind of capability mark for cables/ports into the spec.

You're talking about a completely different thing from cables that claim to handle a certain speed but aren't built well enough to actually do so.

If that was the case, the front non-thunderbolt ports would not be faster, but they are.

Getting USB 2.0 speeds strongly suggests that the cables somehow had horrendous signal integrity...

Anyway I grabbed a 3.1 gen2 SSD and plugged it directly into my 16" M1 Pro (Sandisk Extreme), and I got 850 MB/s read/write with his tool.

And that's supposedly one of the exact drives and laptops he tested. So something is going wrong for him, and it's 90% likely to be cables.

It doesn’t seem particularly likely to be the cables when the same cable plus same external drive but with an Intel Mac results in the expected performance numbers.

In your test, did you use a TB4 cable or a USB data cable?

Just because a marginal cable works on one machine doesn't mean it'll work on another.

I used a USB cable, but I retested with an active TB4 cable with the same results. And again with a passive TB3 cable to the same results.

If the cable is wrecking signal integrity, the port could absolutely change things if the ports have slightly different hardware that's generating the signal. RF does weird things.

Just as a very simplistic analog DC example, if you have wires that are both sitting at 3V but one can only drive 100 mA while the other can drive 1A. If you only draw 50 mA they'd look near identical but as soon as soon as you tried to get close to 100 mA they'd both diverge heavily. You could advertise both at 50 mA for sales purpose but if they were hooked up with a bad high resistance cable they'd look very different.

As a less technical anecdote, I bought one of those usb "sound cards" and it had noise when plugged into the front usb ports but worked fine into the back ones on the same PC.

The sound was transmitted digitally and didn't need that much bandwidth, so the only explanation is "dirty" power on the power wires, I think?

Why did they work with the Intel Mac then?