The first ‘USB4’ external SSDs – Does this have a future?

USB4 is the amalgamation of the USB and Thunderbolt standards that we’ve been promised for some time. The spec is already ready its second revision. We had to wait for fast external SSDs, which on paper can benefit greatly from this development. They didn’t come for a long time, until two ‘USB4’ external SSDs recently arrived in our test lab. You can read how they work and why we write USB4 in quotes in this review.

Why do you want a USB4 SSD?

If you choose an external SSD, you quickly get entangled in the jungle of modern USB standards and the gens and gigabits fly around you. In short, most external SSDs currently use the USB 3.2 Gen2 standard, which effectively enables speeds of up to around 1GB/s. There are also Gen2x2 SSDs, which are twice as fast in theory, but there are hardly any devices to connect them to. I sometimes come across those ports on desktop motherboards, but on laptops you can usually search for a long time.

The other path you can go down is a Thunderbolt SSD. They can reach speeds of up to 40Gbit/s (5GB/s). Here, however, the hookup paradox is exactly the other way around; many laptops do have Thunderbolt these days, but you will hardly find that port elsewhere. In addition, Thunderbolt SSDs have the annoying feature that they don’t backwards compatible are with USB. If you have a device that does not support Thunderbolt, you will not be able to access your data, even at a lower speed.

USB4 is the solution to this problem on paper. It offers the speed of Thunderbolt, but is compatible with older USB standards.

This is how the ‘USB4’ SSDs work

In general, an external SSD is simply an M.2 SSD with its own controller connected to a bridge chip that translates the PCIe/NVMe signal to USB. Official USB4 bridge chips are still not there, however. Although the Thunderbolt spec has been released for a long time, Intel is still de facto the sole manufacturer of controllers for peripherals such as SSDs.

If you look at the product information of the two external SSDs, you will soon find hints at how WD subsidiary brand Sandisk and the Chinese Orico have solved that. Where Orico does use the term USB4, Sandisk calls its Professional PRO-G40 a ‘dual-mode’ SSD. The devices can handle both USB 3.2 Gen2 and Thunderbolt, which in practice amounts to the same as a full-fledged USB4 implementation, but still looks different when it comes to controllers on the internal circuit board.

Once opened – with the Sandisk with the mini-Torx screwdriver, with the Orico only some lateral pressure with the vice helped – it turns out that both SSDs have not one, but two bridge chips. Sandisk and Orico both use an Intel JHL7440 controller for Thunderbolt connectivity, but we also find a ‘regular’ USB 3.2 Gen2 controller on the printed circuit boards. With the Sandisk that is an ASMedia ASM2362, with the Orico a JMicron JMS583. In practice, the SSD first tries to establish a Thunderbolt connection and the USB controller serves as a fallback if that fails. You notice this because it takes a few seconds with a ‘normal’ USB port before your PC recognizes the external SSD.

Orico MTQ-40G

The Orico MTQ-40G, in full the USB4 High Speed ​​Portable SSD Assembly Series 40Gbit/s by the way, may look familiar to you. He shares his Mondrian-like design with de 10Gbit/s-ssd from this manufacturer that we have tested before, although this variant is somewhat larger. Naturally, this faster version is a lot more expensive. The 2TB version we tested stands for 600 euros on Amazon.nl. For the 1TB and 512GB versions, which are also available, you pay 360 and 220 euros respectively.

Between the plastic ‘works of art’ is a rim made of a zinc alloy. A printed circuit board with the aforementioned bridge chips is hidden on the inside. The mounted M.2 SSD combines a Maxiotek MAP1202A-F1C controller, a PCIe 3.0 x4 controller for SSDs without dram cache, with flash memory from the Chinese manufacturer YMTC. So Nand of Chinese manufacture, we don’t see that very often. The complete overprint is: ‘YMC3G004Tb68CA1C0’. We suspect that ‘3G’ means we’re dealing with a somewhat older generation 3D nand with around 100 layers, but public information on this manufacturer’s part numbers is scarce. YMTC stands by the way recently on the United States Export Control List.

Both sides of the PCB are passively cooled with a thin heatsink. They are attached with clips to the SSD itself and the bridge controllers, respectively. This became apparent during a fall test that had not been conceived in advance, fortunately only after the tests had been completed. It is a weak point in the drop resistance of this product, as one of the heat sinks came loose in the process. That doesn’t matter for the functionality of the SSD – after all, SSDs can take a beating – but you did hear the heatsink move when you shook the SSD.

The external SSD comes with a USB-C cable of 30 cm, with an adapter to USB-A attached. The device measures 11.5×6.3×2.1cm and, according to Orico, can achieve a throughput speed of up to 3100MB/s.

Sandisk Professional PRO-G40

Sandisk Professional is the new brand name for products formerly marketed by WD under the G-Technology label. As mentioned, WD does not explicitly call the PRO-G40 a USB4 SSD, but a combination of Thunderbolt 3 and USB 3.2 Gen2. WD specifies separate speeds for both standards: 2700MB/s read and 1900MB/s write via TB3 and 1050MB/s and 1000MB/s respectively via USB 3.2 Gen2.

At 11.1×5.8×1.2cm, the PRO-G40 is especially thinner than the Orico SSD and feels considerably more robust. The outside is finished with a rubbery-feeling silicone; the interior is made of aluminum and should help with the cooling of the ssd. WD has certified the Sandisk Professional PRO-G40 for IP68 water and dust resistance, withstands drops up to 3m and withstands pressures up to 1814kg. The included cable has USB-C on both ends; an adapter to USB-A is not included.

It goes without saying that the PRO-G40 has an SSD of its own making. We know the controller with the imprint Sandisk 20-82-00705-A2 from the WD Red SN700, an NVMe SSD intended for use in nas devices. The flash memory also comes from our own factories, but what the imprint ‘60627’ means exactly remains a guess for us. Unlike the SSD that Orico uses, this SSD does have a dram cache, in the form of a Samsung DDR4 chip (K4AAG16-5WBMCRC).

Comparison table

The table below shows the main differences between the two ‘USB4’ SSDs.