USB-C or Thunderbolt 4 for SSD drive?

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. 👍 🙂

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?

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.

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. 🙂

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.

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.

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.