USB-C or Thunderbolt 4 for SSD drive?

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USB-C or Thunderbolt 4 for SSD drive?

Not sure why I am having a hard time finding this info, but hoping someone here can help. Using an external drive mainly for video for FCPX on my Mac Studio.

I have a 2TB Kingston SSD which boasts "Up to 2100 MB/s". So USB-C is meant to work up to 10GB/s and Thunderbolt, up to 40GB/s. Both interfaces far exceed 2.1GB/s, so what exactly is the point of Thunderbolt for this SSD when USB-C spec is already almost 5x the speed of the SSD. What advantage would I get with Thunderbolt with this SSD?

I also note that Kingston tell me that they do not support using any of their SSD's in any external enclosure, but only directly attached to the motherboard. That's weird because the enclosure manufacturers all say that any compatible SSD will work, which makes sense to me. Putting an HDD in an external enclosure has always worked, so why would that be different for a Kingston SSD, or any other?

Mac Studio

Posted on Dec 14, 2022 9:05 AM

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Answer 1

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Luis Sequeira1

Level 9

67,546 points

Dec 14, 2022 10:29 AM in response to Cartoonguy

Even though nominally the drive can achieve speeds faster than the maximum of USB, I would probably not spend a lot more. It depends on how bad you really need that extra speed - spoiler alert: if you are asking, then you DON'T.

As an example: I can work in FCP using either the internal drive of my MBP (which can do more than those 2.1GBps) and I can use my external SSD connected via USB-C (NOT Thunderbolt), and achieves some 900MBps. The external drive is perfectly capable and does not constitute a bottleneck, editing in 1080 or 4K.

With today's macs and SSD drives, for the most part the limiting factor is the human editor.

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Answer 2

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 10:32 AM in response to Luis Sequeira1

Luis Sequeira1 wrote:

Don't confuse GBps (that's gigaBYTES) with Gbps (that's Gigabits).

The nominal speed of Thunderbolt 4 is 40 Gbps.

The nominal speed of USB 3.2 is 10 Gbps.

If the drive is indeed capable of 2.1GBps that would be above the maximum of USB.

Ah, this is clearly where I am getting it wrong then. The SSD says:

Kingston NV1 2TB M.2 2280 NVMe PCIe Internal SSD Up to 2100 MB/s

So 2100 MB/s does NOT = 2.1 GB/s, because I am confusing bytes and bits. Ugh.

I'm seeing that 2100 Megabytes = 16.8 Gigabits, so indeed, as you say, that's 6.8 GB/s more than the theoretical top speed of USB-C.

So if I go and stick my Kingston 2100 MB/s SSD into a Thunderbolt enclosure, It will be almost 70% faster. And if I used an even faster SSD, then it would also be even faster, but with USB-C, a newer SSD which is say, 3000 MB/s, would be no better than the "slower" SSD via USB-C, but Thunderbolt would take advantage of the faster SSD speed.

Megabits are not Megabytes, but in advertising, the speed is expressed as 10,000 MB/s so who would know? Well, not me, but you do, Luis, so thank you so much. 👍 🙂

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Answer 3

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 10:18 AM in response to Phil0124

Phil0124 wrote:

None. If the enclosure / drive maxes out at 2.1GB/s then you don't get any benefit from using the Thunderbolt port at all. The actual transfer rate is determined by the connected device.

But I am referring to two different enclosures, one an enclosure connected by USB-C and the other, a Thunderbolt enclosure. Like this or this, pictured below. Is there a benefit to spending so much more for a Thunderbolt enclosure when the SSD speed is lower than the USB-C enclosure anyway?

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Answer 4

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 4:18 PM in response to terryb

Yeah, I get that now. Can't believe such a simple thing confused me. Feel a bit dumb for that, but appreciate the helpful comments here.

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Answer 5

Dec 14, 2022 9:34 AM in response to Cartoonguy

Cartoonguy wrote:

Not sure why I am having a hard time finding this info, but hoping someone here can help. Using an external drive mainly for video for FCPX on my Mac Studio.

I have a 2TB Kingston SSD which boasts "Up to 2100 MB/s". So USB-C is meant to work up to 10GB/s and Thunderbolt, up to 40GB/s. Both interfaces far exceed 2.1GB/s, so what exactly is the point of Thunderbolt for this SSD when USB-C spec is already almost 5x the speed of the SSD. What advantage would I get with Thunderbolt with this SSD?

None. If the enclosure / drive maxes out at 2.1GB/s then you don't get any benefit from using the Thunderbolt port at all. The actual transfer rate is determined by the connected device.

I also note that Kingston tell me that they do not support using any of their SSD's in any external enclosure, but only directly attached to the motherboard. That's weird because the enclosure manufacturers all say that any compatible SSD will work, which makes sense to me. Putting an HDD in an external enclosure has always worked, so why would that be different for a Kingston SSD, or any other?

It isn't different. Them not supporting the specific usage just means they won't actually help you if you have an issue with the drive in the enclosure, not that it won't work at all. Its a way for companies to avoid having to use up time and resources on issues that may stem from hardware they have no control over.

Basically it's Kingston saying: "Don't bother us, if the drive doesn't work when you use it in the enclosure".

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Answer 6

Dec 14, 2022 10:17 AM in response to Cartoonguy

Don't confuse GBps (that's gigaBYTES) with Gbps (that's Gigabits).

The nominal speed of Thunderbolt 4 is 40 Gbps.

The nominal speed of USB 3.2 is 10 Gbps.

If the drive is indeed capable of 2.1GBps that would be above the maximum of USB.

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Answer 7

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 10:36 AM in response to Luis Sequeira1

Yes, this is a really good point. I upgraded from an iMac with an HDD RAID set up and so this SSD via USB-C is so much faster anyway that for FCP in HD or 4K, I am getting as much drive access performance as I need in any real world sense. Going any faster doesn't hurt, but it seems that for practical purposes, it's just showing off. 🙂

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Answer 8

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 10:39 AM in response to Luis Sequeira1

I accidentally tagged your other helpful comment as "best answer", but meant it to be this one as this is the complete answer. Don't seem to be able to change it, but anyway, thanks.

Luis Sequeira1 wrote:

Don't confuse GBps (that's gigaBYTES) with Gbps (that's Gigabits).

The nominal speed of Thunderbolt 4 is 40 Gbps.

The nominal speed of USB 3.2 is 10 Gbps.

If the drive is indeed capable of 2.1GBps that would be above the maximum of USB.

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Answer 9

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 10:48 AM in response to Cartoonguy

Point of fact, my 2100 MB/s SSD in a USB-C enclosure shows read/write as about 900 MB/s using Blackmagic disk speed test app, so much less than 2100 MB/s, but probably the max for the USB-C connection. The internal SSD on the Mac Studio gets about 6,000 MB/s, so much, much faster, which is nice, but not really necessary for reading video files compared to the external SSD.

An HDD with RAID 0 could achieve up to 400 MB/s, so even my existing USB-C is over twice the speed. Getting my head around this is really helpful. Thanks again.

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Answer 10

Cartoonguy Author

Level 2

154 points

Dec 14, 2022 11:26 AM in response to Cartoonguy

This also explains why ready made external USB-C SSD drives by Sandisk and Crucial, etc... have drives which max out at about 1050 Mb/s. It's because they know that higher speed with USB-C is no advantage.

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Answer 11

terryb

Level 4

2,626 points

Dec 14, 2022 1:44 PM in response to Cartoonguy

@CartoonGuy, You were correct: 2100MB/s is 2100 Megabytes per second, which is 2.1GB/s or 2.1 Gigabytes per second. The convention is capital 'B' for bytes and lowercase 'b' for bits. So as your calculator screenshot shows, 2100MB/s is equal to 16.8 Gb/s (Giga*bits* per second).

I've seen a few places state Mbit and Gbit to be clear it's referring to bits and not bytes.

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USB-C or Thunderbolt 4 for SSD drive?

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