Tech

USB-C: That’s how fast external SSDs with Thunderbolt 3 are


External NVMe SSDs with a Thunderbolt 3 Type-C connector are expensive. But can the drives with the lightning bolt justify the investment in terms of speed? Our guide explains.

The majority of external NVMe SSDs use the USB 3.2 Gen2 standard via Type-C. The article shows how well

USB-C in practice: This is how fast USB 3.2 Gen2 is

.

How the Type-C with USB 3.2 Gen 2×2 affects external SSDs, you can read in the article ”

Fast but rare: USB 3.2 Gen2x2 in a practical test
“.

The flash for Thunderbolt stands for USB-C in a particularly flexible and fast form. In version 3, the interface transmits up to 40 GBit per second if active cables are used. With passive connectors, the data rate drops by half.

Even if the Type-C connection is mandatory, there is a fundamental difference to other hardware with Type-C connectors: Devices with a Thunderbolt 3 interface require the USB-C connection with the lightning symbol. If they are missing, they simply do not work. Conversely, peripherals with USB 3.2 specification can also be operated on Thunderbolt Type C ports – but only up to a speed of 10 GBit per second.

External TB3 SSDs not necessarily with a speed advantage

Ideally, the gross data transfer rate of Thunderbolt 3 is 5000 Mbytes per second. Realistically, it should be possible to shovel data over the lines at around 3000 MB per second.

To check this with external SSDs, we test the Freecom mSSD Celeritas

Thunderbolt 3 Drive
and

Samsung Portable SSD X5
each with one terabyte capacity. They represent a fairly comprehensive selection of external drives with NVMe SSDs in the housing and Thunderbolt 3 Type-C connector.

External SSDs with a Thunderbolt 3 connection such as the Freecom model mSSD Celeritas are usually more expensive than other type C drives. However, they are not necessarily faster in practice.

Enlarge

External SSDs with a Thunderbolt 3 connection such as the Freecom model mSSD Celeritas are usually more expensive than other type C drives. However, they are not necessarily faster in practice.

© Freecom

What they both have in common is a comparatively high purchase price: Samsung is calling for a whopping 375 euros for the X5 in the aforementioned capacity. And although the Freecom mSSD Celeritas Thunderbolt 3 has been on the market for a while, it still costs at least 310 euros at the time of research.

To ensure a consistently high speed, Samsung has installed a heat sink for the internal NVMe SSD. This is reflected in the price.

Enlarge

To ensure a consistently high speed, Samsung has installed a heat sink for the internal NVMe SSD. This is reflected in the price.

© Samsung

The benchmark test with

Crystaldiskmark
results in extremely high data rates of over 2800 Mbytes per second for both external drives, especially when reading. This means they meet the expectations of Thunderbolt 3. However, the write rates show a different picture: With the Freecom model, they drop to a good 1200 MB per second – which is far less than the manufacturer promises with 2000 MB per second. Samsung’s X5, on the other hand, easily comes into these regions. In the test it reached almost 2400 MB per second.

However, this only applies to the benchmark runs; our practical tests result in much lower transfer rates: The DVD film copying processes show that at best a good 620 MB per second is possible for reading and around 420 MB per second for writing. At the same time, the data rates drop further when small files are transferred: When shoveling our 1000 MP3 music files back and forth, the drives achieve data rates of a good 350 MB per second for reading and around 330 MB per second for writing at best.

These are not bad results, but they are well below what was expected of the Thunderbolt 3 interface. Even more: the transfer speed is provided by external SSDs with USB 3.2 Gen2 as well as Gen 2×2 interfaces. Seen in this way, the surcharge for Thunderbolt 3 SSDs cannot be justified.

You can see an overview of the values ​​determined for the individual SSDs in the table at the end of the article. To make the comparison easier, see results from external NVMe SSDs with USB 3.2 Gen2 and Gen2x2.

Outlook for Type-C: USB 4 and Thunderbolt 4

The next levels of specifications for USB 4 and Thunderbolt 4 show that the USB Type-C interface has broader prospects. In both cases, the twist-proof connector remains the connection of choice. However, peripheral devices such as external SSDs will be a long time coming.

The respective speed levels should be read directly from the USB 4 logos. Two variants are provided with 20 and 40 gigabits per second, even if Thunderbolt 3 acts as the basis.

Enlarge

The respective speed levels should be read directly from the USB 4 logos. Two variants are provided with 20 and 40 gigabits per second, even if Thunderbolt 3 acts as the basis.

© Intel

USB 4 is based on Thunderbolt 3, but with a modification

The upcoming USB 4 takes Thunderbolt 3 as a basis, but changes the standard at the same time. Because there are two tempo variants: The entry point is the 20 GBit per second, which is already known from USB 3.2 Gen2x2. The Thunderbolt 3 speed of 40 GBit per second only has to be achieved in the second expansion stage, which in turn is also called Gen3x2 and requires special cables.

The specification that is available should be identified by a “20” or “40” on the logo and by the type C connector below an arch.

USB 4 does not completely clear up the confusion surrounding USB-C, because the standard is compatible with Thunderbolt, but does not necessarily have to support the protocol. Rather, it is up to the manufacturers whether their USB-4 hardware also includes the Thunderbolt specification. In relation to external SSDs with a Thunderbolt 3 connection, this means that they do not always have to work on the USB 4 Type-C connection. At least it is guaranteed that existing USB devices can be operated, because USB 4 is downward compatible up to version 2.0.

Thunderbolt 4: The ultimate Type-C connector

The solution is to bring Thunderbolt 4, as this standard includes all USB-C predecessors.

Enlarge

The solution is to bring Thunderbolt 4, as this standard includes all USB-C predecessors.

© Intel

Instead of a higher speed level, Thunderbolt 4 relies on the greatest possible compatibility. So it remains at the 40 GBit per second of the predecessor. For this, all functions of USB 4 are mandatory, which can only be included there as options. A USB-C port according to Thunderbolt 4 supports the forwarding of display port signals as well as the power supply of up to 100 watts and can pass through PCI Express connections. In contrast to its predecessor, this version also recognizes the speed level of 20 GBit per second of USB 3.2 Gen2x2.

As one of the first notebooks with a Thunderbolt 4 interface, the Acer Swift (2020) should be available in the fourth quarter. It owes the connection to the Tiger Lake CPU from Intel.

Enlarge

As one of the first notebooks with a Thunderbolt 4 interface, the Acer Swift (2020) should be available in the fourth quarter. It owes the connection to the Tiger Lake CPU from Intel.

© Acer

There is great hope that Thunderbolt 4 will spread quickly to finally untangle the clutter around Type-C. Intel is making a start with the Tiger Lake processors, in which Thunderbolt 4 is integrated. The CPUs for notebooks and ultrabooks belong to the eleventh Core-i generation and can already be found in the first products, such as the update of the Acer Swift 5, which should be available in the fourth quarter of 2020 from a retail price of around 1100 euros.

At a glance: Tempo of external NVMe SSDs

External NVMe SSD with USB-C interface

USB specification

Crystal Disk Mark: sequential read (MB / s)

Crystal Disk Mark: sequential writing (MB / s)

Read DVD movie (MB / s)

Write DVD movie (MB / s)

1000 MP3 read (MB / s)

Write 1000 MP3 (MB / s)

Adata SE760 Portable SSD 1TB

3.2 Gen 2

983.5

809.2

648.95

419.46

408.14

330.39

Adata SE800 Portable SSD 1TB

3.2 Gen 2

975.5

934.1

424.04

372.61

373.24

292.49

Crucial X8 Portable SSD 1 TB

3.2 Gen 2

972.1

958.3

671.40

404.36

447.5

336.65

Patriot PXD USB 3.2 Portable SSD 1 TB

3.2 Gen 2

984.4

898.7

598.05

418.23

371.36

324.56

Samsung Portable SSD T7 Touch 1 TB

3.2 Gen 2

912.5

918.1

400.95

441.12

349.2

306.96

Sandisk Extreme Pro Portable SSD 1TB

3.2 Gen 2

974.3

987.7

627.03

373.91

407.49

281.61

Transcend Portable SSD ESD350C 960 GB

3.2 Gen 2

974.5

940.7

706.97

424.04

446.34

302.27

Seagate Firecuda Gaming SSD 1TB (x4)

3.2 Gen 2×2

1986.9

1990.4

761.16

373.91

557.44

289.37

Seagate Firecuda Gaming SSD 1TB (x2)

3.2 Gen 2×2

1658

1607.3

824.34

376.55

407.45

247.11

Western Digital WD-Black P50 Game Drive SSD 1TB (x4)

3.2 Gen 2×2

1996.2

1955.0

816.46

384.00

459.89

296.70

Western Digital WD-Black P50 Game Drive SSD 1TB (x2)

3.2 Gen 2×2

1672.8

1533.4

802.65

373.59

456.22

298.77

Freecom mSSD Celeritas Thunderbolt 3 Drive 1TB

Thunderbolt 3

2880.4

1204.9

520.11

408.23

329.12

332.73

Samsung Portable SSD X5 1 TB

Thunderbolt 3

2815.6

2392.8

621.55

419.87

356.2

328.70

External NVMe SSD with USB-C interface

USB specification

Crystal Disk Mark: sequential read (MB / s)

Crystal Disk Mark: sequential writing (MB / s)

Read DVD movie (MB / s)

Write DVD movie (MB / s)

1000 MP3 read (MB / s)

Write 1000 MP3 (MB / s)

Adata SE760 Portable SSD 1TB

3.2 Gen 2

983.5

809.2

648.95

419.46

408.14

330.39

Adata SE800 Portable SSD 1TB

3.2 Gen 2

975.5

934.1

424.04

372.61

373.24

292.49

Crucial X8 Portable SSD 1 TB

3.2 Gen 2

972.1

958.3

671.40

404.36

447.5

336.65

Patriot PXD USB 3.2 Portable SSD 1 TB

3.2 Gen 2

984.4

898.7

598.05

418.23

371.36

324.56

Samsung Portable SSD T7 Touch 1 TB

3.2 Gen 2

912.5

918.1

400.95

441.12

349.2

306.96

Sandisk Extreme Pro Portable SSD 1TB

3.2 Gen 2

974.3

987.7

627.03

373.91

407.49

281.61

Transcend Portable SSD ESD350C 960 GB

3.2 Gen 2

974.5

940.7

706.97

424.04

446.34

302.27

Seagate Firecuda Gaming SSD 1TB (x4)

3.2 Gen 2×2

1986.9

1990.4

761.16

373.91

557.44

289.37

Seagate Firecuda Gaming SSD 1TB (x2)

3.2 Gen 2×2

1658

1607.3

824.34

376.55

407.45

247.11

Western Digital WD-Black P50 Game Drive SSD 1TB (x4)

3.2 Gen 2×2

1996.2

1955.0

816.46

384.00

459.89

296.70

Western Digital WD-Black P50 Game Drive SSD 1TB (x2)

3.2 Gen 2×2

1672.8

1533.4

802.65

373.59

456.22

298.77

Freecom mSSD Celeritas Thunderbolt 3 Drive 1TB

Thunderbolt 3

2880.4

1204.9

520.11

408.23

329.12

332.73

Samsung Portable SSD X5 1 TB

Thunderbolt 3

2815.6

2392.8

621.55

419.87

356.2

328.70

->

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PCIe 4.0 vs. 3.0: Do the new RTX 3000 cards benefit from the new interface? Do you maybe even need a new mainboard? Or is PCIe 3.0 still completely sufficient? We test that in this video – but not with any PCIe 4.0 motherboard, but with the motherboard of the HMX 3 – the MSI MEG X570 Godlike. With the 570X chipset, the mainboard is perfectly suited for the new top CPU from AMD, the Ryzen 9 5950X. In addition, the part has some top features, such as 36 PCI-Express 4.0 lanes, 5 slots for M.2 SSDs, & various overclocking tools. As the perfect motherboard for our dream computer that you can win.

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