The cheapest 4TB PCIe 4.0 SSD on Amazon has been tested ahead of Prime Day — but that's not the one I'd recommend

Fanxiang S660 4TB SSD
(Image credit: FanXiang)

Getting your hands on a 4TB SSD for just $158 ahead of Amazon Prime Day seems just too good to be true – but that’s exactly what you’ll get with the FanXiang S660, a high-capacity and low-cost NVMe PCIe 4.0 M.2 SSD. 

Amazon Prime Day is live now with some of the best SSDs and fastest hard drives likely to be available at cut-price deals. 

At 4TB, the S660 is one of the biggest consumer-grade SSDs you’ll find – as well as being the cheapest at $158. It’s certainly the most economical in terms of pure dollars per GB. Just prepare yourself for seriously sluggish performance, according to testing by Serve the Home

Teamgroup MP34: $149.99 at Amazon

Teamgroup MP34: $149.99 at Amazon
No, it is not cheaper than the S660 but the Teamgroup MP34 is a much better known quantity and despite being a Gen 3 SSD, should perform more consistently. A great deal that comes with a five-year warranty. 

The cheapest, and largest, SSD on the market

Its price makes the FanXiang S660 4TB the lowest-cost PCIe 4.0 4TB SSD on the market right now, beating the Silicon Power 4TB UD90 SSD by just $5. But these two are emblematic of a wider trend of cheaper high-capacity SSDs that just fail to live up to expectations, with performance nosediving.

The fastest SSDs out there, including the Samsung 980 Pro, tend to only be sold in variants up to 2TB, and they generally hit read/write speeds of 7,000MB/s. This is true for the Samsung for reads, with writes hitting roughly 5,000MB/s.

The fastest 4TB SSD we’ve seen, meanwhile, is the Crucial T700, which achieved reads of 12,400MB/s and writes of 11,800MB/s. But this will set you back $529.99 on Amazon at the time of writing. 

The S660 4TB, by contrast, reached reads of 5,057MB/s – not bad – but writes of just 406MB/s, which is atrocious for an SSD. Serve the Home achieved these results on CrystalDiskMark.

The site corroborated this with additional results in ATTO – another benchmarking software. Here, the S660 hit reads of 6,738MB/s but writes of an abysmal 365MB/s. What’s worse is that writes drop to 180MB/s in further testing when the drive is filled to the 85% mark.  

When browsing Prime Day on October 10 and 11, it’s important to be wary of how these drives perform in testing and real-world contexts - check out our guide to the best cheap SSD deals to make sure you get the best value and performance to boot.

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Keumars Afifi-Sabet
Channel Editor (Technology), Live Science

Keumars Afifi-Sabet is the Technology Editor for Live Science. He has written for a variety of publications including ITPro, The Week Digital and ComputerActive. He has worked as a technology journalist for more than five years, having previously held the role of features editor with ITPro. In his previous role, he oversaw the commissioning and publishing of long form in areas including AI, cyber security, cloud computing and digital transformation.