Professional PRO-G40 SSD

Over Thunderbolt 3 (40 Gbps) the PRO-G40 is rated for up to 3,000 MB/s read and 2,500 MB/s write. In independent testing it lands around 2,700 MB/s read, with sustained writes stepping down toward roughly 1,900 MB/s once the cache fills — fast enough to scrub multi-stream 4K and 8K footage straight off the drive, and quicker in absolute terms than every USB-based drive in this guide.

The catch is generational. Thunderbolt 3 is a 2017-era interface, and the newer drives in this Pro tier leave it behind: the USB4 ADATA SE920 runs near 3,800 MB/s, and the Thunderbolt 5 OWC Envoy Ultra and LaCie Rugged Pro5 push past 6,000 MB/s. So while the PRO-G40 is genuinely quick, it’s no longer at the front of its class — its 40 Gbps Thunderbolt 3 link and internal NVMe are the ceiling. We score it 7.5: fast, but a step behind the tier’s leaders.

Bottom line on performance: Around 2,700 MB/s of real-world read — plenty for pro video workflows, and the fastest interface among the USB drives — but Thunderbolt 3 speeds now trail the USB4 and Thunderbolt 5 drives alongside it.

This is the category that holds the PRO-G40 back, and it’s worth being precise about why. The drive itself is built on WD/SanDisk’s own NVMe and BiCS TLC NAND, carries a 5-year warranty, and was not among the consumer SanDisk Extreme and Extreme Pro models that failed and lost user data in 2023. But it shares the same SanDisk/WD portable-SSD lineage, and that 2023 episode — Western Digital acknowledged a firmware issue, and a resulting class-action lawsuit remains active and unsettled as of mid-2026 — cast a real cloud over the brand’s data-safety reputation. Some reviewers have also flagged reliability concerns on the PRO-G40 specifically.

For a device whose entire purpose is to safeguard data, that brand-level history isn’t a footnote we can wave away. We score the hardware honestly, then reflect the documented risk transparently — applying a deliberate penalty of 6.5, the amber band. That’s a notch above the consumer Extreme’s 6.0, because the PRO-G40 wasn’t directly implicated in the 2023 failures, but it still sits below where its hardware alone would land — and it’s the single biggest reason it falls short of our top picks.

We treat this the same way we treat long-term-support risk elsewhere on the site. You can read the full background in the reliability note on our main SSD guide.

Bottom line on reliability: Solid hardware under a brand-level cloud. The PRO-G40 escaped the 2023 Extreme failures, but the SanDisk/WD data-loss history earns a deliberate penalty — and an extra-firm reminder to keep a second backup. For a spotless record, the OWC and Crucial drives are the safer call.

Toughness is the PRO-G40’s signature, and it’s outstanding. The drive is rated IP68 — fully dust-tight and able to survive submersion — and engineered to take a 3 m (9.8 ft) drop and up to 4,000 lb (roughly two tons) of crushing force. The chassis is a single piece of forged aluminum that doubles as a heatsink, drawing heat off the internal NVMe so the drive holds its speed instead of throttling under sustained load.

That combination puts it among the toughest drives in the entire guide — well ahead of the IP65 SanDisk Extreme and on par with the field-grade pro drives. Only the LaCie Rugged Pro5 (IP68 plus the same crush and drop ratings) edges it on raw armor. For anyone shooting on location in dust, rain, or rough conditions, this is exactly the protection you want, and it’s the clearest reason to choose the PRO-G40 over a faster but more fragile rival.

Bottom line on durability: IP68 sealing, a two-ton crush rating, a 3 m drop spec, and a forged-aluminum heatsink body — one of the toughest drives we’ve scored, and the PRO-G40’s standout strength.

The PRO-G40 is a dual-mode drive: plug it into a Thunderbolt 3 or Thunderbolt 4 port for full speed, or fall back to a standard USB-C 3.2 Gen 2 (10 Gbps) port on any other machine, where it runs at about 1,050 MB/s. That fallback is a genuine convenience — the drive works on virtually any modern computer, Mac or PC, rather than locking you to Thunderbolt the way some pro drives do.

The qualifier is that the PRO-G40’s value lives entirely on Thunderbolt. On a plain USB-C laptop you get roughly the same ~1,050 MB/s as a basic everyday drive, so most of what you paid for goes unused. And Thunderbolt 3 itself is an older standard than the USB4 and Thunderbolt 5 interfaces around it in this tier. Broad compatibility, then, but you only unlock the speed on a Thunderbolt host — which is why this lands at 7.0.

Bottom line on connectivity: Works everywhere thanks to the USB-C fallback, but full performance needs a Thunderbolt 3/4 port — on plain USB-C it’s no faster than an everyday drive.

This is where the PRO-G40 struggles most. It carries a premium, pro-grade price, yet what you get for it is Thunderbolt 3-era speed — and that’s the problem. Within this same Pro tier, the USB4 ADATA SE920 is both faster and cheaper, and the Thunderbolt 5 drives are dramatically quicker. Measured on speed per dollar, the PRO-G40 is outclassed by newer hardware.

What you’re really paying for is the armor and the badge: IP68 sealing, a two-ton crush rating, and the SanDisk Professional name. If your work genuinely demands a Thunderbolt drive that can be dropped, crushed, or submerged, that protection has real worth and the price starts to make sense. For everyone else, the value case is weak — which is why this lands at 5.5, the lowest sub-score on the card. Unless ruggedness is a hard requirement, your money buys more performance elsewhere.

Bottom line on value: A premium price for older Thunderbolt 3 speed. Justified only if you specifically need IP68 toughness in a Thunderbolt drive; otherwise newer USB4 and TB5 options deliver more for less.

One thing to know up front: unlike the consumer SanDisk Extreme line and the G-DRIVE sibling — both of which include 256-bit AES hardware encryption — the PRO-G40 has no onboard hardware encryption. To protect data you rely on operating-system tools instead: FileVault on macOS or BitLocker on Windows 11 Pro/Enterprise. That’s a real gap for a drive aimed at professionals carrying client work, and it’s the reason this category isn’t scored higher.

What keeps the lightly weighted (5%) Software & Security mark in the amber band rather than lower is the maturity of everything else. The PRO-G40’s dual-mode Thunderbolt/USB firmware is dependable, the Western Digital Dashboard / SanDisk Professional tools handle firmware updates and drive-health monitoring cleanly across Windows and macOS, and the drive plays nicely with OS-level encryption when you enable it. Capable, well-supported software — held to 7.0 by the missing hardware encryption.

Bottom line on software & security: No hardware encryption — plan on FileVault or BitLocker if you carry sensitive data. The firmware and management tooling are mature and dependable, but the absent onboard AES keeps this out of the green.