Three years ago, a new variant of flash memory hit the SSD market which stores four bits of data in each memory cell called QLC. This new QLC NAND flash memory offered 33% better bit density compared to three bits per cell with mainstream TLC NAND. QLC initially arrived as a low-end alternative that provides better density and price, but the trade-off has been worse performance (and endurance). So far the use of QLC NAND has always meant that any drive with QLC belongs in an entry-level market segment, competing against the cheaper TLC NAND SSDs that cut corners on other components. But as more SSD vendors adopt QLC NAND in a wider range of products, some are starting to challenge the assumption that QLC is only for low-quality bargain products.

Prime Time QLC SSDs

Sabrent and Corsair are two very familiar brands that market SSDs based on reference designs from SSD controller vendor Phison. Both brands have followed Phison's lead in using QLC NAND for M.2 NVMe SSDs. The latest and greatest QLC solution from Phison uses its E16 SSD controller, which was the first consumer SSD controller to support PCIe Gen4. The Sabrent Rocket Q4 and Corsair MP600 CORE we are reviewing today are part of the first generation of PCIe 4 SSDs to use QLC NAND: an almost paradoxical combination of a high-end PCIe 4.0 connectivity with low-end QLC NAND. The question to answer is whether if QLC NAND is moving up market into mainstream or high-end products, or is it just PCIe 4.0 support now trickling down to low-end higher-capacity drives? This is what we set to find out with this review.

Corsair MP600 CORE

Many aspects of the Corsair MP600 CORE's spec sheet look pretty high-end. The drive comes with basically the same heatsink as Corsair's high-end TLC drives, albeit in a slightly different color.

Peak performance ratings are close to 5GB/s for reads and 4GB/s of writes, making PCIe 4.0 a necessity to hit those numbers.

Corsair MP600 CORE Specifications
Capacity		1 TB	2 TB	4 TB
Form Factor		M.2 2280 PCIe 4 x4 with heatsink
Controller		Phison E16
NAND Flash		Micron 1Tbit 96L 3D QLC
DRAM		DDR4
Sequential Read (MB/s)		4700	4950
Sequential Write (MB/s)		1950	3700	3950
Random Read IOPS (4kB)		200k	380k	630k
Random Write IOPS (4kB)		480k	580k
Warranty		5 years
Write Endurance		225 TB 0.1 DWPD	450 TB 0.1 DWPD	900 TB 0.1 DWPD
MSRP		$154.99 (15¢/GB)	$309.99 (15¢/GB)	$644.99 (16¢/GB)

The five-year warranty and pricing around $0.15/GB are also indicative that the MP600 CORE isn't exactly entry-level. But on the other hand, the write endurance rating of just over 0.1 drive writes per day is much lower than the usual 0.3 DWPD expected from mainstream consumer SSDs. There are also some unimpressive performance metrics, especially for the smallest 1TB capacity.

Sabrent Rocket Q4

Sabrent's published specs for their Rocket Q4 are quite a bit less detailed, but follow the same general pattern:

Sabrent Rocket Q4 Specifications
Capacity		1 TB	2 TB	4 TB
Form Factor		M.2 2280 PCIe 4 x4 (optional heatsink)
Controller		Phison E16
NAND Flash		Micron 1Tbit 96L 3D QLC
DRAM		DDR4
Sequential Read (MB/s)		4700	4800	4900
Sequential Write (MB/s)		1800	3600	3500
Warranty		1 year (5 with registration)

The Phison E16 controller was originally a very successful bid to be first on the market with a controller supporting PCIe 4.0: Phison ended up having a monopoly on PCIe 4.0 SSDs for over a year, and even some SSD brands that don't routinely use Phison controllers brought out new flagship models based on this controller. But now the successor E18 controller is shipping, as well as competing top of the line PCIe 4.0 drives from both Samsung and Western Digital with their own custom controllers. That leaves the E16 as an outdated part, with performance that is no longer sufficient for a flagship model, and power consumption that is quite high. The E16 is manufactured on 28nm whereas all the other PCIe 4.0 SSD controllers are build on more advanced nodes like 12nm. This means that the E16 is ripe for that cheaper PCIe 4.0 market, which makes sense when adding in some high density QLC.

All that being said, the E16 controller is still a step up from Phison's very successful E12 PCIe 3.0 SSD controller. These PCIe 4.0 controllers are backwards compatible with PCIe 3.0, so even in a system that only supports PCIe 3.0, a drive based on the Phison E16 (like the ones we are testing today) is a bit faster than the E12.

It doesn't currently make sense to pair QLC NAND with the expensive flagship E18 controller, but the E16 has found a second life as Phison's more affordable and mature Gen4 controller when paired with QLC. One consequence of replacing E12+QLC drives with E16+QLC designs is that the E16 controller is physically larger than the compact E12S version's package, and that size difference means the 8TB models cannot yet move up to the E16 controller due to lack of space on a M.2 2280 PCB. That's a shame, because the best showings for QLC NVMe SSDs have been at the largest capacities where huge SLC caches and the highest possible degree of parallelism allow drives to mostly overcome the worst downsides of QLC NAND.

The Competition

In this review, we're comparing the 4TB Sabrent Rocket Q4 and 2TB Corsair MP600 CORE against a variety of other SSDs, from low-end QLC SATA SSDs to high-end gen4 drives with TLC NAND. Particularly interesting points of comparison include:

Intel SSD 670p	PCIe 3.0 x4	SM2265	QLC
Sabrent Rocket Q	PCIe 3.0 x4	Phison E12S	QLC
Corsair MP400	PCIe 3.0 x4	Phison E12S	QLC
Samsung SSD 980	PCIe 3.0 x4	Samsung Pablo	TLC	DRAM-less
WD Blue SN550	PCIe 3.0 x4	WD Custom	TLC	DRAM-less
Seagate FireCuda 520	PCIe 4.0 x4	Phison E16	TLC

AnandTech Storage Bench - The Destroyer

Our AnandTech Storage Bench tests are traces (recordings) of real-world IO patterns that are replayed onto the drives under test. The Destroyer is the longest and most difficult phase of our consumer SSD test suite. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Average Data Rate
Average Latency	Average Read Latency	Average Write Latency
99th Percentile Latency	99th Percentile Read Latency	99th Percentile Write Latency
Energy Usage

The 4TB Sabrent Rocket Q4 turns in excellent scores on The Destroyer, helped greatly by the fact that the test fits entirely within the drive's SLC cache so write latency is minimal. The 2TB Corsair MP600 CORE still has decent overall performance with solid 99th percentile latency scores indicating that it doesn't run into the kind of severe latency spikes that can be common with QLC NAND.

The major downside is that these are among the most power-hungry drives, consuming a bit more energy than the TLC-based Phison E16 drive and significantly more than any of the other drives in this batch.

AnandTech Storage Bench - Heavy

The ATSB Heavy test is much shorter overall than The Destroyer, but is still fairly write-intensive. We run this test twice: first on a mostly-empty drive, and again on a completely full drive to show the worst-case performance.

Average Data Rate
Average Latency	Average Read Latency	Average Write Latency
99th Percentile Latency	99th Percentile Read Latency	99th Percentile Write Latency
Energy Usage

The shorter duration of the Heavy test means that smaller drives can also get good mileage out of their SLC caches, so the 4TB Sabrent Rocket Q4 loses the advantage it had on The Destroyer. The Rocket Q4 and the Corsair MP600 CORE both turn in good scores overall for low-end drives, with clear improvement over the Phison E12 QLC drives.

However, on the full-drive test runs the 2TB MP600 CORE is showing some elevated latency. It's not as bad as on QLC SATA drives and some competing QLC NVMe drives, so overall this isn't a serious concern, but it does emphasize how QLC SSDs need a lot of capacity (and a lot of SLC cache) in order to stay close to the performance of TLC SSDs.

AnandTech Storage Bench - Light

The ATSB Light test represents ordinary everyday usage that doesn't put much strain on a SSD. Low queue depths, short bursts of IO and a short overall test duration mean this should be easy for any SSD. But running it a second time on a full drive shows how even storage-light workloads can be affected by SSD performance degradation.

Average Data Rate
Average Latency	Average Read Latency	Average Write Latency
99th Percentile Latency	99th Percentile Read Latency	99th Percentile Write Latency
Energy Usage

Both of the Gen4 QLC drives provide top-tier performance for the empty-drive runs of the Light test, and they also still provide acceptable performance on the full-drive test runs with no serious latency spikes. As with the other ATSB tests, they come in last place for energy efficiency.

PCMark 10 Storage Benchmarks

The PCMark 10 Storage benchmarks are IO trace based tests similar to our own ATSB tests. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Full System Drive	Overall Score	Average Bandwidth	Average Latency
Quick System Drive	Overall Score	Average Bandwidth	Average Latency
Data Drive	Overall Score	Average Bandwidth	Average Latency

The two PCIe Gen4 QLC drives offer good performance on the Quick System Drive and Data Drive tests, which are relatively shorter and more focused on sequential IO. The longer Full System Drive test with more random IO stresses these drives enough for their low-end nature to show through - in stark contrast to the Intel SSD 670p that manages very good scores on both of the system drive tests.

Burst IO Performance

Our burst IO tests operate at queue depth 1 and perform several short data transfers interspersed with idle time. The random read and write tests consist of 32 bursts of up to 64MB each. The sequential read and write tests use eight bursts of up to 128MB each. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Random Read	Random Write
Sequential Read	Sequential Write

The random read performance from the SLC caches on the Rocket Q4 and MP600 CORE are plenty fast, albeit still not able to match the Intel SSD 670p. Outside the cache, the two Phison E16 QLC drives are definitely slower than mainstream TLC drives, but their performance is fine by QLC standards.

For short bursts of writes that don't overflow the SLC cache, these drives are very fast and their caches are still useful even when the drive as a whole is 80% full.

As is often the case for Phison-based drives, the low queue depth sequential read performance is still not great, but sequential writes are very fast and do reach PCIe Gen4 speeds.

Sustained IO Performance

Our sustained IO tests exercise a range of queue depths and transfer more data than the burst IO tests, but still have limits to keep the duration somewhat realistic. The primary scores we report are focused on the low queue depths that make up the bulk of consumer storage workloads. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Random Read	Throughput	Power	Efficiency
Random Write	Throughput	Power	Efficiency
Sequential Read	Throughput	Power	Efficiency
Sequential Write	Throughput	Power	Efficiency

The random read performance from the Rocket Q4 and MP600 CORE is greatly improved over the earlier Phison E12 QLC SSDs, at least when the test is hitting a narrow slice of the drive that should be entirely within the SLC cache. Random and sequential write results are both decent given that these are in many ways still low-end drives. These two drives are large enough (and have enough SLC cache) to handle much larger bursts of writes than 1TB models, even when the drives are 80% full.

Random Read	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Random Write	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Sequential Read	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Sequential Write	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

The E16-based QLC drives are able to continue scaling up random read throughput (from the SLC cache, at least) long past the points where other QLC drives hit a performance wall. The 4TB Rocket Q4 scales better than the 2TB MP600 CORE, and by QD128 it is handling random reads at 2.5GB/s and still has headroom for more performance. For random writes, the Rocket Q4 and MP600 CORE saturate around QD4 or a bit later, which is fairly typical behavior.

When testing sequential reads, we get the characteristic behavior from Phison controllers: poor throughput until around QD16 or so, at which point there's enough data in flight at any given time to allow the SSD controller to stay properly busy. The sequential write results are messy since both drives run out of SLC cache frequently during this test, and that makes it hard to identify what the performance limits would be in more favorable conditions. But it appears that sequential write speed is saturating around QD2, and stays flat with increasing queue depth except when the caching troubles come up.

Random Read Latency

This test illustrates how drives with higher throughput don't always offer better IO latency and Quality of Service (QoS), and that latency often gets much worse when a drive is pushed to its limits. This test is more intense than real-world consumer workloads and the results can be a bit noisy, but large differences that show up clearly on a log scale plot are meaningful. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

The Sabrent Rocket Q4 and Corsair MP660 CORE show better latency on this test than the other low-end NVMe drives, but all the mainstream TLC drives with DRAM have clear advantages. Even the Samsung 870 EVO has lower latency until it gets close to saturating the SATA link. Between the 2TB MP600 CORE and the 4TB Rocket Q4, the larger drive unsurprisingly can sustain higher random read throughput and its latency climbs more gradually, but the Rocket Q4 does have more transient latency spikes along the way.

Advanced Synthetic Tests

Our benchmark suite includes a variety of tests that are less about replicating any real-world IO patterns, and more about exposing the inner workings of a drive with narrowly-focused tests. Many of these tests will show exaggerated differences between drives, and for the most part that should not be taken as a sign that one drive will be drastically faster for real-world usage. These tests are about satisfying curiosity, and are not good measures of overall drive performance. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Whole-Drive Fill

Pass 1	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Pass 2	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

As is typical for QLC drives based around Phison controllers, the SLC caches on the Rocket Q4 and MP600 CORE are as large as possible: about 1/4 the usable capacity of the drive. Write speeds to the cache hover around or just above the limit of what a PCIe 3 x4 link could handle, and once the cache is full performance drops down to well below the limit of what a SATA link could handle.

Average Throughput for last 16 GB	Overall Average Throughput

Both the 2TB MP600 CORE and the 4TB Rocket Q4 have about the same overall write speed, and they're in the middle of the pack of QLC drives: the older 8TB Rocket Q and the more recent Intel 670p both outperform the Phison E16 drives. And all of the TLC drives naturally sustain higher write speeds than any of these QLC drives.

Working Set Size

Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

Both the Rocket Q4 and MP600 CORE have some disappointing performance drops during the working set size test, suggesting there's background work keeping the drives busy despite all the idle time they get before the test and between phases of the test. But aside from that, we see the expected trends: the MP600 CORE has flat overall performance on account of having 2GB of DRAM for its 2TB of NAND, while the Rocket Q4 shows a slight performance decline for large working sets because it's managing 4TB of NAND with the same 2GB of DRAM.

Performance vs Block Size

Random Read	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Random Write	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Sequential Read	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Sequential Write	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

The two Phison E16 drives with QLC show similar patterns to the E12 QLC drives, but with substantial performance improvements in several places, most notable for random reads. These drives don't have any issues with block sizes smaller than 4kB, but there are performance drops at larger block sizes where the SLC cache runs out while testing random writes.

Mixed IO Performance

For details on our mixed IO tests, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Mixed Random IO	Throughput	Power	Efficiency
Mixed Sequential IO	Throughput	Power	Efficiency

The Sabrent Rocket Q4 and Corsair MP600 CORE deliver excellent performance on the mixed sequential IO test, leading to above-average power efficiency as well. Their performance on the mixed random IO test is not great, and is actually slower overall than what we saw with Phison E12 QLC drives like the original Rocket Q and the MP400.

Mixed Random IO	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB
Mixed Sequential IO	Sabrent Rocket Q4 4TBIntel SSD 660p 2TBIntel SSD 670p 2TBSamsung 870 EVO 4TBSamsung 870 QVO 4TBSamsung SSD 980 1TBSamsung 980 PRO 2TBSeagate FireCuda 520 1TBKingston KC2500 1TBCorsair MP400 1TBCorsair MP600 CORE 2TBSK hynix Gold P31 1TBSabrent Rocket Q 8TBWD Blue SN550 1TB

The earlier E12+QLC drives outperform these new E16+QLC drives across almost all phases of the mixed random IO test, despite using same Micron 96L QLC NAND. On the other hand, the newer QLC drives turn in surprisingly fast and steady results throughout the mixed sequential IO test, though the 2TB MP600 CORE does get off to a bit of a slow start.

 

Power Management Features

Real-world client storage workloads leave SSDs idle most of the time, so the active power measurements presented earlier in this review only account for a small part of what determines a drive's suitability for battery-powered use. Especially under light use, the power efficiency of a SSD is determined mostly be how well it can save power when idle.

For many NVMe SSDs, the closely related matter of thermal management can also be important. M.2 SSDs can concentrate a lot of power in a very small space. They may also be used in locations with high ambient temperatures and poor cooling, such as tucked under a GPU on a desktop motherboard, or in a poorly-ventilated notebook.

Sabrent Rocket Q4 4TB NVMe Power and Thermal Management Features
Controller	Phison E16
Firmware	RKT40Q.2 (EGFM52.3)
NVMe Version	Feature	Status
1.0	Number of operational (active) power states	3
1.1	Number of non-operational (idle) power states	2
	Autonomous Power State Transition (APST)	Supported
1.2	Warning Temperature	75 °C
	Critical Temperature	80 °C
1.3	Host Controlled Thermal Management	Supported
	Non-Operational Power State Permissive Mode	Supported

Our samples of the Sabrent Rocket Q4 and Corsair MP600 CORE use the same firmware from Phison (though Sabrent has re-branded the version numbering). As a result, they support the same full range of power management features. The 4TB Rocket Q4 reports higher maximum power draws for its active power states than the 2TB MP600 CORE, but both drives report the same idle behaviors.

The advertised maximum of 10.58 W for the 4TB Rocket Q4 is alarming and definitely supports Sabrent's suggestion that the drive not be used without a heatsink. However, during our testing the drive never went much above 7W for sustained power draw, which is more in line with the maximum power claimed by the 2TB MP600 CORE (which also tended to stay well below its supposed maximum). In practice, these drives can get by just fine without a big heatsink as long as they have some decent airflow, because real-world workloads will almost never push these drives to their maximum power levels for long.

Sabrent Rocket Q4 4TB NVMe Power States
Controller	Phison E16
Firmware	RKT40Q.2 (EGFM52.3)
Power State	Maximum Power	Active/Idle	Entry Latency	Exit Latency
PS 0	10.58 W	Active	-	-
PS 1	7.14 W	Active	-	-
PS 2	5.43 W	Active	-	-
PS 3	49 mW	Idle	2 ms	2 ms
PS 4	1.8 mW	Idle	25 ms	25 ms

Note that the above tables reflect only the information provided by the drive to the OS. The power and latency numbers are often very conservative estimates, but they are what the OS uses to determine which idle states to use and how long to wait before dropping to a deeper idle state.

Idle Power Measurement

SATA SSDs are tested with SATA link power management disabled to measure their active idle power draw, and with it enabled for the deeper idle power consumption score and the idle wake-up latency test. Our testbed, like any ordinary desktop system, cannot trigger the deepest DevSleep idle state.

Idle power management for NVMe SSDs is far more complicated than for SATA SSDs. NVMe SSDs can support several different idle power states, and through the Autonomous Power State Transition (APST) feature the operating system can set a drive's policy for when to drop down to a lower power state. There is typically a tradeoff in that lower-power states take longer to enter and wake up from, so the choice about what power states to use may differ for desktop and notebooks, and depending on which NVMe driver is in use. Additionally, there are multiple degrees of PCIe link power savings possible through Active State Power Management (APSM).

We report three idle power measurements. Active idle is representative of a typical desktop, where none of the advanced PCIe link or NVMe power saving features are enabled and the drive is immediately ready to process new commands. Our Desktop Idle number represents what can usually be expected from a desktop system that is configured to enable SATA link power management, PCIe ASPM and NVMe APST, but where the lowest PCIe L1.2 link power states are not available. The Laptop Idle number represents the maximum power savings possible with all the NVMe and PCIe power management features in use—usually the default for a battery-powered system but rarely achievable on a desktop even after changing BIOS and OS settings. Since we don't have a way to enable SATA DevSleep on any of our testbeds, SATA drives are omitted from the Laptop Idle charts.

Both the Sabrent Rocket Q4 and Corsair MP600 CORE show quite high active idle power draw, a consequence of their use of a PCIe Gen4 controller made on 28nm rather than something newer like 12nm. However, there's no problem with the low-power idle states except for Phison's usual sluggish wake-up from the deepest sleep. This seems to be worse for higher capacity drives, with the 4TB Rocket Q4 taking about an eighth of a second to wake up.

Conclusion

The Sabrent Rocket Q4, Corsair MP600 CORE and related drives form the first crop of QLC drives to support PCIe Gen4. It is clear from our testing that the PCIe Gen4 support doesn't automatically make these drives high-end. The Gen4 capability on these drives isn't a big deal for overall performance, though they are incrementally faster than most PCIe Gen3 QLC drives.

The Rocket Q4 and MP600 CORE definitely provide faster sequential transfer speeds than other QLC drives and entry-level TLC drives, but for random IO the Intel SSD 670p often steals the spotlight despite only supporting PCIe gen3 on its host interface. Optimizing for fast sequential IO is a great way to produce big numbers for marketing purposes, but the tradeoffs made by the Intel 670p seem for the most part to better for the real world.

These Gen4 QLC drives inherit the most notable problem with the Phison E16 controller - the high power consumption- and this adds on to the poor efficiency of QLC NAND. The combination still isn't particularly prone to overheating or thermal throttling during normal consumer use, but heatsinks do make more sense for these drives than on most M.2 SSDs currently shipping with fancy heatsinks. There's not much demand yet for PCIe Gen4 SSDs for notebooks, but these drives are definitely ill-suited to that role.

Previous QLC NVMe drives had already proven that QLC can be an acceptable route to mainstream NVMe performance, provided that the drive has a high enough capacity. The Rocket Q4 and MP600 CORE show that peak performance can be extended even further, but they don't do much to illustrate how worst-case performance can be improved to further reduce the downsides of QLC.

NVMe SSD Price Comparison April 9, 2021
	500 GB	1 TB	2 TB	4 TB
Sabrent Rocket Q4 PCIe Gen4, QLC		$149.98 (15¢/GB)	$279.98 (14¢/GB)	$689.98 (17¢/GB)
Corsair MP600 CORE PCIe Gen4, QLC		$154.99 (15¢/GB)	$309.99 (15¢/GB)	$644.99 (16¢/GB)
Mushkin DELTA PCIe Gen4, QLC		$159.99 (16¢/GB)	$299.99 (15¢/GB)	$599.99 (15¢/GB)
Sabrent Rocket Q QLC	$64.99 (13¢/GB)	$109.98 (11¢/GB)	$219.98 (11¢/GB)	$599.98 (15¢/GB)
Corsair MP400 QLC		$109.99 (11¢/GB)	$229.99 (11¢/GB)	$593.99 (15¢/GB)
Mushkin ALPHA QLC				$569.99 (14¢/GB)
Intel SSD 670p QLC	$69.99 (14¢/GB)	$114.99 (11¢/GB)	$249.99 (12¢/GB)
Samsung SSD 980 DRAMless, TLC	$69.99 (14¢/GB)	$129.99 (13¢/GB)
WD Blue SN550 DRAMless, TLC	$59.99 (12¢/GB)	$109.99 (11¢/GB)
SK hynix Gold P31 TLC	$74.99 (15¢/GB)	$134.99 (13¢/GB)
WD Black SN750 TLC	$69.99 (14¢/GB)	$139.99 (14¢/GB)	$299.99 (15¢/GB)	$799.99 (20¢/GB)

As we saw with the TLC drives when the Phison E16 controller first brought PCIe 4 support to consumer SSDs, that extra bandwidth comes at a significant premium. For the more mainstream capacities, the E16 QLC drives are substantially more expensive than the PCIe Gen3 QLC drives using the older E12 controller, or even the recent Intel SSD 670p. However, at 4TB, the premium for Gen4 on a QLC drive is a lot smaller. Mainstream PCIe Gen3 TLC drives are also cheaper than the Gen4 QLC drives, for capacities below 4TB. At and above 4TB there really aren't many options, and almost all of the are QLC-based. It is disappointing that upgrading to PCIe Gen4 has so far precluded these Phison drives from offering the 8TB capacity that is available from Phison E12 drives. That will likely come as 28nm controllers make way for newer models on 12nm or smaller.

These Gen4 QLC SSDs are not a great general-purpose storage solution; they certainly don't combine PCIe Gen4 and QLC and come out with only the best advantages of each. But they are still suitable for some use cases, especially centered around higher capacities.