While most external SSDs achieve transfer speeds of up to 1,050 MB/s, the new model from SanDisk’s Professional series goes full throttle: thanks to the Thunderbolt 3 connection, the storage solution achieves up to 2,900 MB/s for reading and 1,900 MB/s for writing, according to the manufacturer. With this rapid speed and a robust design, the aim is to appeal to all those who also want a reliable and fast storage solution for outdoor use. Our Sandisk Professional Pro-G40 SSD test clarifies whether the purchase is worthwhile.
Technical data
| Storage capacity | 1 TB; 2 TB (test model); 4 TB |
| Interface | USB 3.2 Gen 2 (10 Gbps, Type-C); Thunderbolt 3 (40 Gbps, Type-C) |
| Max. Read/write speed (MB/s) | 3.000/2.500 |
| Special features |
IP68 water and dust protection, shockproof from a drop height of up to 3 m, shockproof up to 1,800 kg |
| Scope of delivery | external SSD, USB-C to USB-C cable (0.20 m) |
| Dimensions | 111 mm x 58 mm x 12 mm (L x W x H) |
| Weight | 121,3 g |
| Warranty period | 5 years |
| Price |
€ 304.78 * |
Sandisk Professional Pro-G40 SSD review: design and build quality
Photographers, videographers and creators looking for a robust external SSD for outdoor use are undoubtedly the target group for the Sandisk Professional Pro-G40 SSD. The dark gray external storage solution can take a beating.
The robust and largely rubberized housing is not only protected against dust and water thanks to IP68 certification, it is also designed to withstand shocks of up to 1,800 kg and drops from a height of three meters without any problems.
With a weight of 121.3 grams and dimensions of 111 mm x 58 mm x 12 mm, the Pro-G40 SSD is also heavier and larger than most other external SSDs – as the size comparison with the Samsung T7 and the comparatively tiny Crucial X9 Pro (our test) also shows.
Nevertheless, the SSD is small enough to easily fit into any bag or backpack. The scope of delivery only includes a USB-C to USB-C cable with Thunderbolt 3 support with a length of just 20 centimeters. This is sufficient, but a little more length wouldn’t have hurt either.
Additional tools and software solutions are not included, not even in the memory of the external SSD. However, these can be downloaded easily and free of charge from the manufacturer’s website if required. With WD Dashboard or WD Utilities, some practical tools are available.
The robust construction of the Sandisk Professional Pro-G40 SSD is absolutely impressive in the test. The workmanship leaves little to be desired. With the possible exception of the rubber coating, which quickly acts as a dust and dirt magnet. Scratches on the top are also quickly recognizable, as can be seen from our used test sample.
Praiseworthy: SanDisk offers a full five-year manufacturer’s warranty on the drive.
Performance test of the Sandisk Professional Pro-G40 SSD
The Sandisk Professional Pro-G40 SSD has a single USB-C port on the underside. However, this has the special feature that it is a Thunderbolt 3 port.
With the additional feature that USB 3.2 Gen 2 Type C is also supported. Depending on which port you use the external SSD on, you either get the maximum speed of 40 Gbit/s or a lower speed (10 Gbit/s) with significantly reduced power consumption and lower heat generation.
SanDisk itself states speeds of up to 3,000 MB/s for sequential writing and up to 2,500 MB/s for sequential reading for the Pro-G40 SSD on its own website – whereas the packaging states 2,700 MB/s / 1,900 MB/s.
Values that we can also confirm in the benchmark test. If we connect the external SSD via USB-C, it achieves 968.57 MB/s read and 751.99 MB/s write in the AS-SSD benchmark. Very good results that are roughly on a par with the Crucial X9 Pro. Only the 4K performance and access times are slightly behind.
However, things get interesting when we connect the Sandisk Professional Pro-G40 SSD to a Thunderbolt port, as the values shoot up noticeably. AS-SSD attests the external SSD a whopping 2,699.99 MB/s for read and 2,289.28 MB/s for write.
The CrystalDiskMark even shows 3,148.00 MB/s reading and 2,590.82 MB/s writing. The 4K values and access times also benefit significantly from the switch to Thunderbolt 3.
USB-C:
Thunderbolt 3:
This makes a huge difference in the long term, especially with large files, because the Pro-G40 SSD maintains a constant working speed even with large amounts of data. In USB-C mode with 10 Gbit/s, however, the speed falls slightly behind the Crucial X9 Pro in the endurance test.
| Test | USB-C | Thunderbolt 3 |
| Seq. read (AS-SSD) | 933.89 MB/s | 2699.99 MB/s |
| Seq. write (AS-SSD) | 745.14 MB/s | 2.289.27 MB/s |
| 4K | 24.04 MB/s / 31.35 MB/s | 37.68 MB/s / 13.90 MB/s |
| 4K-64Thrd | 102.13 MB/s / 106.51 MB/s | 1.110.63 MB/s / 320.87 MB/s |
| Access time | 0.120 ms / 0.119 ms | 0.031 ms / 0.386 ms |
| SEQ1M (CrystalDiskMark) Read | 1.018.01 MB/s | 3.148.00 MB/s |
| SEQ1M (CrystalDiskMark) Write | 782.12 MB/s | 2.241.67 MB/s |
In fact, it is true that the SSD gets significantly warmer when connected via Thunderbolt. However, at around 46 degrees Celsius, the external storage solution is still cooler than most competitors with metal housings, even under continuous load. There is hardly any noticeable increase in temperature when using USB-C.
Sandisk Professional Pro-G40 SSD test: Conclusion
The Sandisk Professional Pro-G40 SSD scores with unparalleled performance, not least thanks to its Thunderbolt 3 connection. Read and write speeds, as well as 4K tests and access times when connected via Thunderbolt, are second to none and relegate all the external SSDs we have tested so far to the back of the pack.
The speeds when connected via USB-C are also impressive and are roughly on a par with the competition, with the SanDisk drive only weakening a little in the 4K 64Thrd values.
However, there is one drawback and that is the price. With an RRP of €510.99 for the 2 terabyte version we tested, the external SSD is more than twice as expensive as the Crucial X10 Pro, which also offers excellent speeds, but is not as robust.
If you’re prepared to spend this much money and can benefit from the advantages of Thunderbolt 3 connectivity, this is an excellent external SSD that will be hard to beat.
Sandisk Professional Pro-G40 SSD
Access times
Transfer rate (read)
Transfer rate (write)
Value for money
92/100
The Sandisk Professional Pro-G40 SSD is extremely robust and unbeatable in terms of speed (so far). The only point of criticism is the price, which is more than twice as high as the fastest external SSDs on the market. However, these do not quite reach the speed of the Pro-G40.
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