Adata SC740 1TB External SSD Review

Could Adata’s $75 SC740 1TB be the ultimate pocket drive? And could USB 3.2 Gen2x2 be the ultimate drive standard? And, what if the USB 3.2 Gen2x1 drive we test today turns out to perform at Gen2x2 levels?

A very brief trip down memory lane down might be needed to answer the above questions, as it involves a different standard called Thunderbolt 3:  Fundamentally an external device standard for PCIe 3.0, its controllers increased the PCIe interface’s 32Gbps to a combined 40Gbps by piggybacking DisplayPort signals over the same cable(s). And, to increase interoperability with USB Type-C, it added USB 3.2 Gen2x1. After that, everything appeared to stop.

While we could talk about how Intel took over development, submitted it to the USB Implementer’s Form (USB-IF), and renamed the combined standard USB4, the reality is that we haven’t seen any noticeable improvements since Thunderbolt 3 controllers were upgraded to support USB 3.2 Gen2x2 and rebranded as Thunderbolt 4: Our first USB4 40Gbps drive couldn’t even reach the 4000MB/s (32Gbps) of its data interface, and plugging it into a USB 3.2 Gen2x2 controller often resulted in a performance increase. So, maybe we should stick to USB 3.2 Gen2x2?

Labeled as an ordinary USB 3.2 Gen2x1 device (10Gbps = 1250MB/s) and stated by its manufacturer to have a maximum transfer rate of only 1050MB/s, that the  SC570 1GB is priced according to its rating could be a real treat if it outperforms its rating.

While the integrated cable seems like a cheap way to get around adding more connectors, it’s also a reasonable way of preventing those extra connections from getting plugged with dirt. The cable slips in and out of a rear clip as illustrated in an Adata marketing photo (click here to see it), thereby providing additional crud protection to the Type-C cable end.

Other than that, the package includes a user guide and the drive itself a five-year limited warranty.

Adata SC740 1TB Test Configuration

We tested the SC740 1TB against our most recently reviewed 1TB pocket drives, Adata’s USB4 40 connected SE920 and Sabrent’s Thunderbolt 3 connected Rocket Nano XTRM, expecting the new drive to perform only as well as the Thunderbolt 3 drive’s USB mode. We’ll try to reserve the surprises for our benchmark results charts.

CPU	AMD Ryzen 9 7950X: 16C/32T 4.5-5.7 GHz, 64MB L3 Cache, Socket AM5
CPU Cooler	Alphacool Core 1 Aurora, VPP655 with Eisbecher D5 150mm, NexXxoS UT60 X-Flow
Motherboard	ASRock X870E Taichi, Socket AM5, BIOS 1.28 (07-27-2023)
Graphics	Powercolor Red Devil Radeon 6750 XT: 2324-2623MHz GPU, 12GB GDDR6
Memory	Crucial Pro OC Gaming Edition DDR5-6400 2x16GB (32GB) CL32-38-38-96 1.30V
System Drive	Crucial T700 w/hs Gen5 PCIe 2.0TB SSD

Adata SC740 1TB Performance Results

Completing a Sandra drive test produces a result that, when clicked, presents an information pop-up describing the hardware used to generate that result. Here’s a sampling of the test data it provided for each of our test devices following its “Physical Disk” test.

For those who need a math reminder, 10Gbps is 10000Mbps: Divide that by eight to go from megabits per second to the test’s stated megabytes per second, and 1250MB/s is the best result that a 10Gbps device could hope to achieve. But here the SC740 is moving 2021MB/s…how?

The only way that the SC740 could possibly be getting the performance seen in Sandra is by enabling twin pathways (USB 3.2 Gen2x2) rather than having just one pathway going to two connectors (USB 3.2 Gen2x1). The old Rocket Nano XTRM certainly drops to Gen2x1 mode when connected to the motherboard’s front-panel Gen2x2 interface, and those performance patterns even hold true through our AIDA64 test.

The biggest problem with the above results in that they’re all outdated: Sandra hasn’t been updated since 2023, and AIDA64 dropped its drive read test around the same time, forcing us to revert to that earlier version. Things got weird when we switched to 3DMark’s real-world-approximate test patterns, with the rear controller performing worse when equipped with Thunderbolt-equipped drives.

It wasn’t the game loading test, but the transfer test, that seemed to be the problem, almost as if Thunderbolt can’t transfer reads and writes at the same time. As silly as that thought appeared to be, it also applies to the PC Mark tests.

ATTO shows that Sequential Reads are very fast, and Sequential Writes very slow in Thunderbolt mode. The drive that doesn’t support any Thunderbolt technology whatsoever, the SC740 is most consistent.

The same pattern continues through CrystalDiskMark, with the SC740 becoming the normalizer between the motherboard’s front (USB-only) and rear (Thunderbolt-native) interfaces. The latency measured on one of its test brings back that silly thought we had two paragraphs ago.

Diskbench demolishes the Thunderbolt 4 drive, but only in Thunderbolt 4 mode. The only time the cheap SC740 loses is when the SE920 is connected to the cheaper USB-only front-panel interface.

Next is our comparison of game-pattern, application-pattern, and large file transfers. The “slowest” drive finishes only 6% on average behind the “fastest” drive’s best result. Oh, and its best result is on USB 3.2 Gen2x2!

Remember that the SC740 is also only half the price of the Thunderbolt-enabled drives…ouch.

The SC740 serves up some wonderful test results that really cause us to question whether the drive we received is the actual product that Adata is currently shipping. Meanwhile the Thunderbolt-equipped drives we compared show incredibly fast reads with writes that are so slow that many users would be better off sticking with USB 3.2 Gen2x2.

Adata SC740 1TB (SC740-1000G-CBU)
Pros	Cons
Gen2x2 performance at Gen2x1 pricing Lightweight and compact Five-year Warranty	Looks and feels a little cheap
The Verdict
That the SC740 we received performs twice as well as it should causes us to question whether it’s a representative sample. Fortunately, Adata’s ample warranty should give you an opportunity to find out.

We’d like to suggest that everyone who can afford this drive buy it, connect it to a motherboard’s USB 3.2 Gen2x2 or USB4 interface, run CrystalDiskMark and report those findings in our comments section. Those unable to get results similar to ours from a sufficiently-fast motherboard interface should feel free to cite today’s review when contacting Adata support.

More than just a technology bargain, the SC740’s ability to squeeze 20Gbps performance from what the manufacturer says is a 10Gbps interface makes it a technical miracle worthy of our rarely-issued Innovation award. (Even an internal miscommunication that resulted in the interface being mislabeled at half its performance potential would still rank the drive as a top deal.)