With the decades-long shift in the PC space towards laptops and portable storage, I have always been a bit surprised that we have not seen much in the way of USB4-capable portable SSDs thus far. The 40Gbps version of the USB standard was introduced in late 2019 with the first controllers following around a year later – but USB4 portable SSDs have been a far more recent introduction. As a result, there has been a pretty large gap between USB4 hosts and USB4 devices, as we have been waiting for the latter to catch up.
But this year we are finally seeing the external storage market’s major players step up with their first generation of USB4 external SSDs. Essentially placing a PCIe 4.0 x4 SSD behind a USB bridge, these latest generation of portable SSDs are promising a big jump in sequential read and write performance, essentially unlocking drive performance that was previously bottlenecked by 20Gbps USB connections.
To that end, SanDisk in recent months has released an updated version of its long-lived Extreme PRO lineup of portable SSDs that adds USB4 support – the aptly named SanDisk Extreme PRO Portable SSD with USB4. With a new transfer interface and seemingly new internals as well, SanDisk is promising that one of these drives can already come close to saturating a USB4 connection, something that is well within the capabilities of a PCIe 4.0 x4 drive. With that degree of performance in a portable SSD, combined with SanDisk’s typical ruggedized housing, and the company is pretty much promising everything one could want in a high-performance portable SSD.
| SanDisk Extreme PRO Portable SSD with USB4 Specs | |
| Capacity | 4TB |
| USB | 40Gbps USB-C (USB4 Gen 3×2) |
| Protocol | NVMe |
| Rated Read Speed | 3.8GB/sec |
| Rated Write Speed | 3.7GB/sec |
| Dimensions | 110mm x 68.6mm x 12mm (5.51 x 2.7 x 0.47 in) |
| Weight | 172g (0.38 lbs) |
| Warranty | 5-Year |
| Water Resistance | IP65 |
Though with a street price of $480 for the 4TB model we are looking at today, that performance does not come cheap. NAND prices have been on an upswing in recent months, which is not doing SanDisk or buyers any favors, but the Extreme PRO USB4 was never a cheap drive to begin with – it is very much a premium product within SanDisk’s lineup. And even compared to SanDisk’s competitors in the USB4 SSD space, the company is still asking for a premium price at this time.
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SanDisk Extreme PRO USB4 Portable SSD 4TB Hardware Overview
Starting off our look at the SanDisk Extreme Pro Portable SSD itself, one thing that stand-alone product photos do not do justice to is the sheer physical size of the drive. While at first glance this looks like a slightly refined version of SanDisk’s long-standing Extreme PRO drive series casing – complete with the orange and black hole in one corner – this is in fact a completely new case, designed in SanDisk’s industrial style to match its other drives.
And that new case is because SanDisk did not just stuff updated electronics into their existing case, but they needed to make a larger case to house the USB4 drive – much larger. Whereas the last generation drive was 110 x 57 x 10 mm in size, or about 62.7cm3, the USB4 version of the drive explodes to about 110 x 68.6 x 12mm, for a total volume of about 90.6cm3. In other words, the USB4 version of the drive is roughly 44% bigger than the previous version of the drive – and previous Extreme PRO drives already had a reputation for being big. Ultimately this is still very much a portable drive – albeit one that calls for bigger pockets – but it is the biggest Extreme PRO yet, as the series is now approaching the size of an iPhone.
Size aside, the updated Extreme PRO drive carries over all of the ruggedization features that the drive family is known for. The heavy rubber exterior adds both some heft and some serious cladding to protect the drive, and like its predecessors its IP65 rated for water resistance.
Along the bottom of the drive is the sole port, with the Extreme PRO remaining powered entirely over USB-C, allowing the whole thing to operate off of a single cable.
Printed on the back of the drive are all of the regulatory and model details, including the capacity in large print and its USB4 compatibility as part of the product name.
Looking at the complete packaging, the drive itself is most of what comes in the product box. Otherwise, the only other piece of equipment included is a USB-C to USB-C cable. SanDisk is no longer including a C-to-A cable as well, which had come with past generations of the Extreme PRO.
Next, let us get to performance.
