People have always demanded larger and larger SSDs to store all their data at the fastest performance tier. We're finally seeing ultra-high-performance, high-capacity drives with PCI-Express 4.0 support thanks to Phison's E18 controller. We've encountered the Phison E18 in many recent reviews—it has catapulted Phison from being an interesting midrange SSD controller vendor to the market leader within a short time. If you've read our other Phison E18 reviews, the Sabrent Rocket 4 Plus PCB should look familiar to you since it matches the Phison reference design exactly. Just like Kingston, Team Group, and Corsair, Sabrent took the Phison design and used it for their own product. This is certainly a valid approach as Phison probably knows best how to design an SSD that works well with their own controller. As expected, a DRAM cache is included for the mapping tables of the SSD, which helps with random writes. Due to the higher capacity requirement, both sides of the PCB are populated with flash chips, so the 4 TB capacity can be achieved with eight 512 GB chips, which are more expensive per GB than 256 GB chips, but cheaper than 1 TB chips.

The NAND flash chips are Micron's latest and greatest 176-layer B47R. While other vendors like Corsair are creating new products for the component change from 96-layer to 176-layer, at higher pricing, of course, Sabrent just silently transitioned the Rocket 4 Plus from 96-layer to 176-layer. While we're not fans of silent component changes, it's fine in this case because you're getting better performance. According to Sabrent, all stock of 96-layer Rocket 4 Plus of all capacities is depleted, and anything you can buy in stores is 176-layer. To verify, you can check the firmware version of the SSD, which should show "R4PB47.2" for B47R; older ones are "RKT4P1.2."

Just like other Phison E18 drives, the Rocket 4 Plus 4 TB shows excellent synthetic performance results; all scores are near the top of our charts. Random and sequential IO beats the Samsung 980 Pro and WD Black SN850, the strongest competitors. Basically, nothing but Phison E18 drives lead our scoreboard here. Phison made sure a lot of optimization went into getting these synthetic scores high enough, which is why our real-life testing is so important—it runs actual applications, something that's much harder to optimize for. Our real-life testing is also performed with 80% of the drive filled, which is a more realistic scenario and limits the drive in the way it uses its pseudo-SLC cache.

In our real-life test suite, the 4 TB variant of the Rocket 4 Plus achieves impressive results that are even slightly better than other E18 drives of smaller capacity we have tested before because the controller can utilize more parallelism due to the higher number of NAND chips and NAND dies inside. The Rocket 4 Plus is now able to match the WD Black SN850—the fastest SSD we ever tested. Using some very impressive algorithms to mitigate the issues DRAM-less brings with it, the DRAM-less WD Black SN770 is just as fast. The Rocket 4 Plus is 1% faster than the Samsung 980 Pro, and Kingston KC3000 (E18 + B47R, but smaller capacity). Compared to the fastest PCIe 3.0 drives, the performance uplift is 3–5%. Value M.2 NVMe drives are up to 20% slower, and the aging SATA drives are at least 25% behind.

The pseudo-SLC cache of the Rocket 4 Plus is "large" in absolute terms with 400 GB, but in relative terms, it's just 10%, so not that big. Considering the size of bursty write loads stays constant no matter how big the target drive, this is a perfectly fine design choice. Sustained writes are excellent, filling the whole 4 TB capacity completes at 2.7 GB/s—one of the best results we've ever seen in this test. Of course, momentarily stopping the write activity will have the SLC cache free up capacity immediately, so full write rates are available as soon as you give the drive a moment to settle down.

Sabrent includes a preinstalled heatspreader foil with the Rocket 4 Plus, which is certainly better than nothing; in our thermal stress test, we still encountered throttling relatively quickly. It seems the higher number of NAND packages on the PCB increases heat output compared to smaller capacity versions. That said, encountering thermal throttling in daily use is highly unlikely—we had to hammer the drive with 350 GB of incoming data in 60 seconds to get it to throttle. Once the drive throttles, the behavior is quite aggressive. Performance pretty much stops for a few seconds, so a higher thermal limit with a more gradual throttling algorithm would have been better. If you want better cooling, do consider Sabrent's M.2 SSD heatsink; an excellent design with lots of mass, it had the drive avoid thermal throttling completely in our testing.

The Sabrent Rocket 4 Plus 4 TB is currently listed on various sites for $750, which is a lot of money not only in absolute terms, but also in relation to the smaller capacity models. The 4 TB at $750 is $188 per TB, and a 1 TB Rocket 4 Plus costs $130, while the 2 TB variant costs the same: $130 per TB. I asked Sabrent about that, and their response was that the larger capacity NAND chips do get more expensive per GB. Not sure if the difference is really that much, but when looking at other 4 TB M.2 SSD options available on the market, Sabrent does have competitive pricing. There are actually very few PCIe 4.0 4 TB TLC drives available. There's the PNY CS3040 ($600, 1st gen PCIE 4.0, an old Phison E16, not faster than modern PCIe 3.0 SSDs) and Corsair MP600 Pro ($720, Phison E18 + 96-layer). Everything else is Phison E18+B47R. Of those, there's the Team Group Cardea A440 Pro SE, Kingston KC3000, Corsair MP600 Pro LPX, Seagate FireCuda 530, and Silicon Power XS70. Out of all these drives, which are pretty much identical, the Rocket 4 Plus is the most affordable model. The strongest competitor is the Silicon Power XS70, which gives you a proper metal heatsink for $5 more.

While a high-end 4 TB M.2 SSD is definitely an amazing thing to have, considering the price, there are several alternatives. For example, you could buy two 2 TB M.2 SSDs and save $250 in the process. Obviously, this only makes sense if you have the M.2 slots to spare, which is probably not the case if the 4 TB purchase is an upgrade. Modern motherboards have tons of SATA ports, so you could go for a 4 TB TLC SATA SSD for around $400 and pair it with a fast 2 TB E18 drive for $260, which totals 6 TB of storage for the price of the 4 TB Rocket 4 Plus, but you'd have to move your hot games and data to the fast storage drive, and the same goes for the combination of a fast SSD paired with an HDD for archiving purposes. All these alternatives are compromises—if you want the best performance with the convenience of huge capacity, you'll have to pay for it.