SanDisk Professional PRO-G40 SSD review

SanDisk Professional PRO-G40 SSD : Two minute review

Western Digital has divided up the branding of its products into sub-brands, and the SanDisk Professional brand is specifically aimed at supporting customers with specialist needs.

In this grouping are external RAID enclosures, desktop G-DRIVE products and various flash drive readers, along with the subject of interest to us today, external SSDs.

Existing SanDisk customers will be familiar with its Extreme PRO portable drives and how they offer excellent value for money for ordinary users. But the SanDisk Professional PRO-G40 isn’t cheap, moving it from something home users might consider into more of a business solution.

There are two aspects to this design that aim to justify its cost over an Extreme series drive, and those are its resilience and its performance.

On picking it up, it’s evident that the exterior of the PRO-G40 is much more refined than the Extreme PRO products, which are primarily plastic. The PRO-G40 combines a metal form with a rubberised coating on the underside and sides, delivering up to 4000lb of crush resistance and the ability to survive up to a 3m drop.

It’s also IP68 dust/water resistant, which means it can handle getting wet or dusty without it destroying the drive, although we probably wouldn’t take it swimming.

SanDisk has high confidence that the rugged enclosure on the PRO-G40 should keep the NAND technology inside safe and demonstrate this with a 5-year limited warranty.

Being rugged is good, but the more significant selling point here is the performance of this external drive, which matches some internal SDD storage.

Exactly how fast it operates is dependent on the speed of the system it is connected to and the connection technology that is used. The PRO-G40 works with both USB and Thunderbolt interfaces, with the fastest transfer speeds achievable with Thunderbolt.

The quoted performance is 2700MB/s reading, and 1900MB/s writes over Thunderbolt (40Gbps), though this drops to closer to 1000MB/s over USB 3.2 Gen 2 (10Gbit).

By using Thunderbolt, it is possible to copy a 50GB file to the PRO-G40 in around 30 seconds if the internal SSD can keep up.

This performance hints that if you only have USB 3.2 Gen 2 ports, then it probably isn’t worth the extra expense over a SanDisk Extreme Pro, Crucial X8 or similar. But for those with Thunderbolt 3 or USB 4.0, a significant performance benefit might make it worth the extra investment.

SanDisk Professional PRO-G40 SSD: Price and availability

(Image credit: Mark Pickavance)How much does it cost? From $279.99 / £297.99When is it out? It is available nowWhere can you get it? Widely available from the larger online retailers in most regions.

But even by Thunderbolt-connected SSD standards, this cost is expensive, and those wanting something more affordable with a similar capability should look at the Plugable product range

We’ve noticed that the price of this drive has been reduced recently, reflecting the reduced cost of NAND modules and high levels of competition in this sector.

Bought directly from the makers, the 1TB and 2TB models are £297.99 and £495.99 in the UK. In the USA, they can be bought for $279.99 and $399.99.

Therefore they are more expensive outside America, by between 20% and 30%.

Prices in the rest of Europe are slightly lower than UK costs, but not by much.

For those curious how the cost is divided between the enclosure and the NVMe drive inside, these drives utilise the SN750 SE SSD. That module costs just $95.99 for the 1TB model.

That makes the PRO-G40 enclosure over $200, assuming the retail cost of the module inside, a price that SanDisk almost certainly doesn’t pay internally.

This reveals that this is an overpriced product even with the recent cost reductions, as it is twice the price of a good USB 3.2 Gen 2 design, like the Crucial X8, for the same capacity of storage.

Value: 3/ 5

SanDisk Professional PRO-G40 SSD: Design

(Image credit: Mark Pickavance)Tough enclosureNo carry caseLacks USB-A adapter

As external SSDs go, the PRO-G40 might not be the smallest one we’ve looked at, but it feels remarkably sturdy. And, although we never drove a vehicle over ours, it can probably withstand the 4000lb of crush weight that SanDisk claims for it.

The rubberised TPU used on the sides and back of the drive helps prevent it from scratching other hardware if it is placed in the same bag, like one used for a laptop.

That’s a good thing because out of the box, even at this price, SanDisk doesn’t include a pouch for the drive and USB-C cable. An omission that third-party case makers are probably already working to address.

The other item that is missing, and really should have been included, is a USB-C to USB-A cable.

The cable is on the short side and only supports USB-C or Thunderbolt 3 (Image credit: Mark Pickavance)

What you get with this drive is a short 20 cm cable that works for both Thunderbolt and USB 3.2 Gen 2 connection, but no means to connect the drive to a USB-A, only USB-C ports.

These adapters aren’t expensive. Crucial includes one for free with the X8, and the PRO-G40 box doesn’t include one is unfortunate.

We didn’t try to open our review hardware, but there are four visible screws on the top that might help open it for those willing to void their 5-year warranty and negate the dust and water resistance of this device.

Design: 4 / 5

SanDisk Professional PRO-G40 SSD: Features

Only 1TB and 2TB optionsNo hardware EncryptionApple Pre-formatted

The most significant flaw of the SanDisk Professional PRO-G40 is that the biggest capacity available is only 2TB. Whereas the SanDisk Extreme series drives come with 500GB and 4TB options, the PRO-G40 is either 1TB or 2TB.

The issue here is that the designers of the PRO-G40 evidently decided that the NVMe inside would be the SN750 SE, and that doesn’t come in 4TB.

A quick scan through the Western Digital range of retail SSDs reveals that the biggest NVMe drives they make are 2TB, with the one exception being the WD Black SN850X.

Crucial, Sabrent, Corsair, Seagate and others make multiple M.2 4TB designs, but more confusingly, SanDisk has 4TB SSDs in its SanDisk Extreme Portable SSD V2 range.

Not sure how the PRO-G40 only gets a maximum of 2TB, but that’s what it got.

The performance of external storage is dictated by the bandwidth of the NAND modules onboard and the controller/bridge chip configuration.

In this design, the bridge chip is an Intel Titan Ridge chip, the JHL7440 Thunderbolt 3 controller that first appeared in 2018, designed for PCIe Gen 3 operations.

But that silicon doesn’t handle USB, so a secondary Asmedia ASM2362 is used for a PCI Express(downstream port) to USB3.1(UFP) bridge.

The maximum speed of the JHL7440 is 40Gbps over Thunderbolt, and the Asmedia ASM2362 can shift 10Gbit/s over USB.

For those purchasing the PRO-G40 for their Apple Mac, all they need to do is take it out of the box and connect it to an Apple-branded computer, as the drive is pre-formatted with APFS.

(Image credit: Mark Pickavance)

Microsoft Windows users will discover that the drive doesn’t appear if they connect it, sadly.

They will need the technical knowledge and confidence to use the Windows management console to delete the existing partition and create a new NTFS or exFAT volume for it to work.

This choice seems odd since other drive makers deliver drives with a dual boot model that allows both Apple and PC owners to get a drive configured without needing specialist knowledge.

SanDisk includes no software of any kind for this drive on the device and seems to have assumed that it will be used exclusively with Apple Time Machine on that brand of device.

It’s also worth noting that the SN750 SE drive that is used here doesn’t support hardware encryption. While it is possible to use with software encryption, like Microsoft BitLocker, this doesn’t offer the same level of protection that hardware-encrypted storage has.

Features: 4 / 5

SanDisk Professional PRO-G40 SSD: Performance

CrystalDiskMark 8.0.4 Benchmark (Image credit: Mark Pickavance)High speeds on ThunderboltGood speeds on USB

It’s interesting to note that when we first saw the PRO-G40, we only tested it on a PC with Thunderbolt 3 interface, and we got good but not exceptional performance.

We’ve reviewed several external SSDs that support either Thunderbolt or USB 3.2 Gen 2×2, and the increase in bandwidth that these interfaces offer has a dramatic impact on the speeds of reading and writing.

On the Thunderbolt 3 PC, the speeds topped out at around 2,770MB/s reads with 2,570 MB/s writes, and under USB-C, those numbers dropped to around 1,000MB/s in both directions.

That’s better than the 2700MB/s reading and 1900MB/s that SanDisk quotes, but it isn’t as quick as this drive can go.

Plugging it into a recent Lenovo ThinkPad Z16 Gen 1 laptop, with its USB 4.0 ports that are backwards compatible with Thunderbolt 3, it received a significant speed boost.

Over this interface, the PRO-G40 managed over 3,150MB/s reads and 2,700MB/s writes using the 2TB model.

That makes the PRO-G40 the fastest external Thunderbolt drive we’ve tested recently by some margin. The only drive we’ve seen that is close to this is the OWC Envoy Pro FX, and that costs even more than the PRO-G40.

Over USB, the best performance we attained was around 1,000MB/s for both reading and writing, but that’s the interface, not the drive.

The speed of this drive over Thunderbolt might justify the cost in some quarters if they have Thunderbolt or  USB 4.0. But for users with only USB 3.2 Gen 2, there are cheaper choices that can match the physical resilience and USB performance for a substantially smaller outlay.

(Image credit: Western Digital)Performance: 5 / 5

If you want the very fastest Thunderbolt external SSD, then the PRO-G40 is probably wearing that crown for now.

But the maximum capacity is only 2TB, and the exorbitant cost compared with comparable USB devices like the Corsair X8 or other SanDisk options make it a little less compelling.

SanDisk Professional PRO-G40 SSD: Report card

Should you buy a SanDisk Professional PRO-G40 SSD?

(Image credit: Mark Pickavance)

Buy it if…

Don’t buy it if…

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