Phison E31T ES 2TB Review: The performance per watt champion

Comparison Products

As the E31T ES is a PCiE 5.0 SSD, we need to see how it handles the existing crop of 5.0 drives, along with upcoming drives as well. This breaks down to a few different basic hardware configurations. Phison was the first to market with its E26 controller, used at first in slower options like the Crucial T700 before being optimized with faster releases — the Crucial T705 and the write-optimized Sabrent Rocket 5 being prime examples. Alternative, comparable controllers are represented by the InnoGrit IG5666-based Adata Legend 970 Pro and upcoming drives based on Silicon Motion’s SM2508 controller.

We also want to see how the E31T handles the very best last-generation PCIe 4.0 SSDs. These include the SK hynix Platinum P41, Samsung 990 Pro, and WD Black SN850X. We also want to compare a couple of high-end budget drives, one based on Maxio’s MAP1602 — the Silicon Power US75 is a suitable representative — as well as the popular DRAM-equipped Crucial T500. Lastly, to show the difference between what a mid-range 5.0 drive like the E31T ES can do compared to a mid-range 4.0 drive, we have added in the Samsung 990 EVO.

Trace Testing — 3DMark Storage Benchmark

Built for gamers, 3DMark’s Storage Benchmark focuses on real-world gaming performance. Each round in this benchmark stresses storage based on gaming activities including loading games, saving progress, installing game files, and recording gameplay video streams. Future gaming benchmarks will be DirectStorage-inclusive and we also include notes about which drives may be future-proofed. 

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The Phison E31T ES’s 3DMark performance is good but not great. It’s certainly fast enough to be a game drive, if that’s your thing, especially looking forward with Phison’s DirectStorage-optimized firmware. The PCIe 5.0 SSDs with DRAM and the full interface bandwidth — the T705, SM2508 ES, and Rocket 5 — can all push more bandwidth than the E31T ES. That said, the latter is more than a match for any PCIe 4.0 drive, which is important as it can be run in a 4.0 slot and drives with the E31T may end up being cost-competitive with some of the best last-generation drives. 

Trace Testing — PCMark 10 Storage Benchmark

PCMark 10 is a trace-based benchmark that uses a wide-ranging set of real-world traces from popular applications and everyday tasks to measure the performance of storage devices. The results are particularly useful when analyzing drives for their use as primary/boot storage devices and in work environments. 

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The PCMark10 results follow in line with 3DMark, which is generally but not always the case. The E31T ES’s numbers aren’t earth-shattering by any means, but they need to be taken within a wider context. This especially means looking at power consumption and suitability for laptops, which we will discuss more in detail later. 

Console Testing — PlayStation 5 Transfers

The PlayStation 5 is capable of taking one additional PCIe 4.0 or faster SSD for extra game storage. While any 4.0 drive will technically work, Sony recommends drives that can deliver at least 5,500 MB/s of sequential read bandwidth for optimal performance. In our testing, PCIe 5.0 SSDs don’t bring much to the table and generally shouldn’t be used in the PS5, especially as they may require additional cooling, though the Phison E31T could change that. Check our Best PS5 SSDs article for more information.

Our testing utilizes the PS5’s internal storage test and manual read/write tests with over 192GB of data both from and to the internal storage. Throttling is prevented where possible to see how each drive operates under ideal conditions. While game load times should not deviate much from drive to drive, our results can indicate which drives may be more responsive in long-term use. 

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Our PS5 tests have changed to a small degree over time due to various system updates, but the values are still within a small range. Most of the faster drives come close to the PCIe 4.0 interface limit on the PS5 read test, while the write to and read from M.2 tests tend to encounter other bottlenecks like the PS5 internal SSD's encryption algorithm.

That said, the E31T ES breaks the mold with its bandwidth in our "read from M.2" transfer test, rising above previous generation SSDs. It's a bit weird and we're not entirely sure what has changed, as we previously assumed it was the internal SSD holding back performance. We checked the numbers twice, however, as well as having tested a couple of other SSDs in recent days, and that 264 MB/s result is legit. It's not a big deal in the grand scheme of things, but drives based on the E31T should become a great option for the PS5 — if the price is right. 

Transfer Rates — DiskBench

We use the DiskBench storage benchmarking tool to test file transfer performance with a custom, 50GB dataset. We write 31,227 files of various types, such as pictures, PDFs, and videos to the test drive, then make a copy of that data to a new folder, and follow up with a reading test of a newly-written 6.5GB zip file. This is a real world type workload that fits into the cache of most drives. 

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Copy transfer rates can vary significantly from one drive to another, especially when factoring in the drive generation. A PCIe 5.0 SSD with maximum bandwidth, like the Rocket 5, has a higher ceiling than a last-generation SN850X. Slower drives like the 990 EVO suffer even more. So it’s not too hard to predict where the E31T ES should land in our DiskBench testing — above the PCIe 4.0 SSDs, but below the faster 5.0 ones. This in and of itself doesn’t mean much, but if you’re someone who transfers files around a lot it could make a difference in daily operations due to lower waiting times.

If your intention is to put this drive into an enclosure this can also be important, but at these speeds you are looking at USB4 or Thunderbolt enclosures — which can support the host memory buffer (HMB) feature as well — and an E31T drive might be a great choice there because it’s more efficient and won’t overheat like previous PCIe 5.0 options. Sustained performance may be lower, however, reflected in our write saturation testing further below. 

Synthetic Testing — ATTO / CrystalDiskMark

ATTO and CrystalDiskMark (CDM) are free and easy-to-use storage benchmarking tools that SSD vendors commonly use to assign performance specifications to their products. Both of these tools give us insight into how each device handles different file sizes and at different queue depths for both sequential and random workloads. 

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Starting with ATTO, the E31T ES performs as expected with writes but has some variance when it comes to reads. Given the performance levels demonstrated in other tests, we can chalk this up to our sample being a work-in-progress. It is likely due to the controller firmware, possibly amplified by the use of flash that’s new to the market. We saw no real world impact from this, but our results here show that there are kinks to work out when it comes to innovative products like the Silicon Motion SM2508 or the E31T.

CDM tells us a little more about the sequential performance, with good results for the E31T. This is expected as it has more bandwidth available to it than PCIe 4.0 SSDs like the 990 Pro and T500. However, its sequential read performance at a queue depth of 1 — and this is a common workload for many things, like game or app loading — falls behind the T500 and Platinum P41. There isn’t a huge difference here, but we can hypothesize that the T500’s six-plane flash and the Platinum P41’s less-dense flash dies both enable more interleaving for this workload.

This dovetails well with our expectations mentioned earlier, which is to say that the BiCS8 flash may have some architectural optimizations for smaller I/O. CDM shows this off in its full glory with the E31T ES scoring the lowest 4KB QD1 random read latency in our testing to date. Specifically, it beats the original 990 Pro, which was long our champion after it came out. The E31T sample also beats even very fast drives when it comes to 4KB QD1 random write latency. On top of this, the drive can reach IOPS that were once unthinkable for a DRAM-less drive, demonstrating once and for all that the era of needing DRAM and a full eight channels for impressive SSD performance is over.

We caution you from reading too much into the 4KB latencies because real-world performance will differ from synthetic testing, especially for workloads that fall out of the temporary cache. Additionally, many day-to-day workloads involve larger I/O or sequential workloads even where you wouldn’t expect it. Lastly, there are many places for bottlenecks such that subjective feel between one SSD and another can be practically nonexistent. On the other hand, there’s no doubt that the E31T ES performs exceptionally well in this classic benchmark.

Sustained Write Performance and Cache Recovery

Official write specifications are only part of the performance picture. Most SSDs implement a write cache, which is a fast area of pseudo-SLC (single-bit) programmed flash that absorbs incoming data. Sustained write speeds can suffer tremendously once the workload spills outside of the cache and into the "native" TLC (three-bit) or QLC (four-bit) flash. Performance can suffer even more if the drive is forced to fold, which is the process of migrating data out of the cache in order to free up space for further incoming data.

We use Iometer to hammer the SSD with sequential writes for 30 minutes or more to measure both the size of the write cache and performance after the cache is saturated. We also monitor cache recovery via multiple idle rounds. This process shows the performance of the drive in various states as well as the steady state write performance. 

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The 2TB E31T ES writes in the single-bit pSLC mode at up to 8.8 GB/s for around 50 seconds, indicating a cache that could be as large as 440GB. This is not as large as it could be — 2TB of TLC flash in pSLC mode allows for up to ~680GB — but it's still a very large cache. Phison has generally been reserved in its caching with recent designs — the Sabrent Rocket 4 with the E27T controller is a great example — possibly in part because the Crucial T500 and its E25 controller had inconsistent write performance with the latter’s large cache. Large caches are often more popular these days, though, since normally that’s where the drive is operating for day-to-day writes.

Once the E31T ES leaves the pSLC mode, it hits a direct-to-TLC mode at around 1.5 GB/s. This is significantly slower than what we would expect from this flash. There are reasons why it would be this low, although simply being a trade-off for the larger cache while avoiding a slow folding state for as long as possible is a good enough explanation. If the drive runs out of space and has to empty the pSLC cache forcibly, this folding state makes for slower writes — in this case, 800 MB/s or less — with less consistent performance and higher latencies.

For those wanting higher sustained writes speeds, we certainly think this flash can deliver it, but it doesn’t make too much sense to optimize a drive like this in that manner. 

Power Consumption and Temperature

We use the Quarch HD Programmable Power Module to gain a deeper understanding of power characteristics. Idle power consumption is an important aspect to consider, especially if you're looking for a laptop upgrade as even the best ultrabooks can have mediocre stock storage. Desktops may be more performance-oriented with less support for power-saving features, so we show the worst-case.

Some SSDs can consume watts of power at idle while better-suited ones sip just milliwatts. Average workload power consumption and max consumption are two other aspects of power consumption but performance-per-watt, or efficiency, is more important. A drive might consume more power during any given workload, but accomplishing a task faster allows the drive to drop into an idle state more quickly, ultimately saving energy.

For temperature recording we currently poll the drive’s primary composite sensor during testing with a ~22°C ambient. Our testing is rigorous enough to heat the drive to a realistic ceiling temperature. 

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The E31T controller, being a four-channel DRAM-less solution built on TSMC N7, unsurprisingly is super efficient even compared to the N6 SM2508. It’s quite simply the most efficient hardware we’ve ever seen. The combination of this controller with efficient flash is bound to be a winner. It will work in laptops, it will work in PS5s, it will work in HTPCs and many other machines, too. There’s no compromise here for great performance.

Generally speaking, lower power consumption correlates with thermal output. This isn’t 100% true for a variety of reasons, since temperature can impact efficiency and there are other factors such as controller and IHS design. However, to simplify for most SSDs that come across our desk, our power results made us expect the E31T ES would run relatively cool.

This proves correct, as the drive reached a maximum of 56°C in our testing and only briefly at that. The 55°C realistic maximum is 18°C below the first throttling point, which leaves plenty of thermal headroom. While the SM2508 could potentially be used in a laptop — at least at 1TB — the E31T is the first PCIe 5.0 SSD controller that will be put into drives that actually can be safely used without a heatsink, which includes in laptops.

We nevertheless still recommend a heatsink if a drive is used in a desktop. This can be a motherboard-included M.2 heatsink, a third party heatsink, or your own solution. This is especially true if you’re buying a drive for heavier use or sustained workloads, although as per the Sustained Write section above we think there are better options than the E31T ES for that purpose. Also, if you have an X670E motherboard, be aware of a motherboard bug that impacts 5.0 SSDs. 

Test Bench and Testing Notes

We use an Alder Lake platform with most background applications such as indexing, Windows updates, and anti-virus disabled in the OS to reduce run-to-run variability. Each SSD is prefilled to 50% capacity and tested as a secondary device. Unless noted, we use active cooling for all SSDs.

 Phison E31T ES Bottom Line 

The Phison E31T SSD controller is an accomplishment only slightly dimmed by the recent sample of SMI’s faster SM2508. These are two amazing platforms coming out at nearly the same time, promising two very different things. While the SM2508 is the more traditional eight-channel, DRAM-equipped powerhouse, the E31T is a more accessible four-channel, DRAM-less design. There are places for both of these in the marketplace and it’s great to see more efficient PCIe 5.0 options coming to the table. This is especially true with the older Phison E26 and InnoGrit IG5666 controllers both requiring heatsinks and being essentially impossible to run outside of enthusiast desktop PCs.

While the SM2508 we tested could theoretically be used in a laptop, the E31T ES is the first PCIe 5.0 drive we’ve seen that could actually be recommended for such use. Moreover, while this might almost seem moot as laptops generally support PCIe 4.0 SSDs at the fastest, the E31T might still be up your alley. This is because its excellent power efficiency would be even higher in a 4.0 slot. This means lower power consumption on the whole, but also lower thermal output. It’s by no means the only drive that will work well, but it’s an extra option for those that want the highest performance without sacrificing elsewhere.

Full PCIe 4.0 performance can already be had with decent efficiency in several popular mainstream solutions, though. Maxio’s MAP1602 with YMTC flash — usually TLC flash, but there are QLC alternatives — is a very popular combination, as seen by the Silicon Power US75 throughout this review. Crucial’s T500 remains popular as it’s the main drive available with DRAM that’s efficient enough for everyday laptops. Phison’s E27T controller also works wonders in drives like the Sabrent Rocket 4. These are all based on 12nm designs with their own advantages and disadvantages, but the 7nm node ultimately leaves the E31T a cut above if you truly want the newest and shiniest hardware.

Realistically, though, you can get enough performance out of some mid-range PCIe 4.0 SSDs like the Teamgroup MP44 and WD Black SN770, or maybe the WD Blue SN580 or WD Blue SN5000. These drives are all great up to and including 2TB, and QLC flash may be acceptable at 4TB in drives like the Crucial P3 Plus. After all, the E31T does not have 4TB specifications just yet, although ultimately that capacity will come. It’s probably not a good idea to go with some of the high-end options with eight channels and DRAM — the WD Black SN850X being the most prominent example — if you’re trying to have a svelte solution for your mobile experience. For desktops and workstations, though, you can afford to go with the faster options, including the previously listed PCIe 5.0 heavy hitters.

Coming back around, it’s impossible for us to not sing praises for the E31T. It’s powerful, it’s efficient, and it’s the future. With availability and reasonable pricing it’ll be the backbone of new builds everywhere, even for PCIe 4.0 systems. We know you want 4TB drives and Phison knows this too, but 2TB remains the sweet spot for now and our sample performed admirably.

The E31T doesn’t have the raw bandwidth of eight-channel solutions, but its use of new flash results in an extremely efficient and effective platform that can provide an excellent experience for almost anything. It shouldn't be the first choice for a sustained write workhorse drive, either, but there will be drives for that, and the firmware will be smoothed out before release for better all-around consistency. If you’re looking for a fast drive with no drawbacks, anything built on this technology should be an easy pick.

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