Samsung 990 2TB SSD Review: New flash, familiar speeds

Samsung is back with another solid-state drive, and this time it’s something a little bit different. The 990 is a QLC-based 990 EVO Plus, positioned as a budget drive that can still push a lot of bandwidth. It’s a little late to the game and not quite what was rumored for the 990 QVO, but it does bring some new technology to the table. We’re always interested in seeing what Samsung puts out, and this time is no different. It should not be confused as being part of Samsung’s Pro line or, for that matter, the EVO line, so keep that in mind.

The drive has its ups and downs, but in this challenging market, and for a budget drive, that’s to be expected. Samsung is still well-regarded for its name and reliable hardware, even as there has been a massive push towards enterprise, away from the consumer side. Samsung has, in fact, given some ground in the SSD space for many years, even as it produces some of the most common OEM drives. So while this is not a Crucial situation, it’s best to jump into this review with the right expectations about what this drive is and isn’t. It’s a budget drive with full Gen 4 throughput that hits the most common capacities with sufficient performance and power efficiency. It’s not meant to be a throne-taker.

It’s also thankfully not another 990 EVO situation – that drive felt somewhat underwhelming by the time it arrived, even when pitted against budget drives – but the 990 is also not a QLC rallying call. It’s a competent drive that mostly hits the right notes, as intended. Given how scarce Samsung QLC drives have been, and how much demand its QLC flash surely has elsewhere, it can feel like Samsung is throwing consumers a bone, though it would be crass to put it that way. We instead think this is smart positioning by the company as it knows the future is with QLC and the technologies used in this flash (even if first shown two years ago at ISSCC) point firmly at an ambitious future. The 990 just lets you own a piece of that.

Samsung 990 Specifications

The Samsung 990 is only available at 1TB and 2TB capacities, with MSRPs of $269.99 and $529.99, respectively. These prices are very high, as you can get competing drives like the Crucial P310 for substantially less, and in fact even the TLC-based WD Black SN7100 costs less. But Samsung has historically launched with MSRPs well above actual market price. You should be able to get the drive at significantly lower prices after launch, but the “Samsung tax” may still apply. We’ll get into what that means throughout the review.

This limited capacity range is unfortunate, but enables Samsung to pack the flash into just one package, which reduces PCB space so that any OEM variant can be used in multiple M.2 form factors and will always be single-sided. Less than 1TB is also not enough for these denser dies if you want good performance. That leaves 1TB and 2TB as the target capacities, which also makes sense in a market where 4TB+ is getting exceptionally expensive. We’ll eventually see 2Tb dies to make single-package 4TB a reality, but that’s further along in Samsung’s roadmap.

The drive can reach 7,250 / 6,450 MB/s for sequential reads and writes and up to 850K / 1,200K random read and write IOPS. Peak performance is attained at 2TB, where you have the optimal amount of interleaving or parallelization: Sixteen 1Tb dies means four dies for each of four flash channels, the typical ceiling. However, as these are four-plane dies, you still get 32-way interleaving at 1TB with eight dies, which is enough to get good performance with just two dies per channel. Less than that is much less ideal, and more than that introduces additional overhead, especially for budget controllers. The math changes with six-plane and 2TB dies, but for this flash, 1TB is the reasonable minimum, with 2TB offering the best performance.

The drive is rated for approximately 4W of power draw across the two capacities, when looking at both reads and writes. Check our power results below to see how accurate that is. The drive is rated for 400TB of writes per TB capacity, which is high for QLC flash – we would typically see maybe 300TB, which is one-half of the TLC standard – but also indicates a very high drive writes per day (DWPD) rating. This is due to the warranty only covering three years rather than the normal five, so the amount of writes per year is significantly higher. This is atypical, so requires further explanation.

For those who live for TBW and write endurance, this illustrates why TBW often looks better on paper. Spreading 400TB over three years works out to roughly double the daily write allowance of a typical 300TBW / five-year QLC drive. Most people will never approach either number, and they will live with the shorter coverage window. However, if you intend to hammer the drive with writes to the point of exceeding TBW within the three-year warranty period, then this could be good. Although you really shouldn’t use a budget DRAM-less QLC-based drive for that type of workload. However, that option exists and is rarely the case with a QLC-based drive. As a final note, the drive does support TCG Opal 2.0 for encryption.

Samsung 990 Software and Accessories

Samsung’s Magician software is the gold standard for consumer SSDs. This is an SSD toolbox with all the features you need. It displays system and drive health information, including SMART, and checks whether your drive is legitimate. You can also benchmark your drive and use any optional features, such as encryption. The software is also essential for keeping the drive’s firmware up to date, although you can also download that from the first link.

Samsung 990: A Closer Look

The 990 has an SSD controller, a single NAND flash package, and power management circuitry. There is no DRAM package present. This is a single-sided drive, which is ideal for compatibility and cooling. There is a lot of free space on the PCB, and by putting distance between the controller and flash, there is separation to mitigate component heat generation. This would also help if a heatspreader or heatsink were to be added. Without this space, the drive could be sold in a shorter form factor, which is particularly useful for OEM drives.

The label has information about the drive, such as the date of manufacture (DOM), model, serial, the PSID, and the power rating. We always caution that you not take certain drive information as being conclusive about the hardware. For example, you should not assume TLC or QLC flash from a drive’s TBW. Likewise, you shouldn’t rely on the labeled power rating – and this is done more often on M.2 2230 drives for portable devices – as any indication of drive power efficiency. Here we have 3.3V / 1.85A, which indicates potential power draw over 6W. Now, the power ratings given on spec sheets will often be average and not peak, and will be separated as read or write rather than mixed. In fact, this drive’s load power states can reach a peak of 5.90W via SMART, which is much above the rated average ~4W. We track both peak and average in our testing.

We always enjoy reviewing Samsung drives with a focus on the technicals, as the manufacturer remains a leader in many ways. The 990, in particular, requires some extra description to be fully appreciated. Simply looking at the benchmark results might make the technology seem underwhelming – to be honest, this is very much a budget drive, even taken in the best light – but that doesn’t mean Samsung phoned this one in. In fact, there are signs of deliberate design here, and some of the decisions could help sell this drive. Samsung still has to get the pricing right, of course, but what else is new?

Let’s start with the controller. The 990 is using the PiccoloQ, which is the QLC flash version of the Piccolo. The Piccolo is utilized on the 990 EVO and 990 EVO Plus, two TLC-based drives. In all cases, it’s a four-channel, DRAM-less design, which limits performance and capacity. In both cases, the controller takes up to 2,400 MT/s flash – this is more than enough to saturate PCIe 4.0 – and the interior design is the same. This means it’s a Samsung 5nm part with multiple ARM Cortex-R8 cores and a single R5 core. If the Piccolo stands out in any way, it’s that it offers a PCIe 5.0 x2 option in addition to the standard 4.0 x4 interface. This option or mode has limited usefulness, though, and nothing in the 990 would change that if enabled for the PiccoloQ.

So, not much new on the controller front, but the use of this controller at the 990’s rated speeds does give us some more information. Namely, we know the 990 EVO runs more slowly because it’s using flash slower than 2,400 MT/s, 1,600 MT/s Samsung V6P TLC, to be precise. If we look at Samsung’s V7 QLC flash, it can run at that same speed. This is why the originally speculated 990 QVO with that flash was targeted at the same speeds as the 990 EVO. Things have changed since then. This drive could have been the 990 QVO, but with the EVO and EVO Plus lines going DRAM-less this generation, we suspect the QVO tier was “promoted” to the plain 990 name, and the 990 now targets the 990 EVO Plus’s specs

The evidence to back this up, which also supports the loose 990 QVO rumor, is that Samsung does have a V7 QLC OEM drive: the BM9C1. This is the cousin to the PM9C1 line with OEM 990 EVO and 990 EVO Plus (PM9C1b) variants. The BM9C1 is available down to M.2 2230 and uses the same PiccoloQ as the 990 (the QLC version of the 990 EVO/EVO Plus’s Piccolo). It’s just limited to the same speeds as the 990 EVO, as it’s running at 1,600 MT/s. We have to be careful here, though, as Samsung’s V9 QLC press release indicates a 60% I/O improvement, which, with the V9 being 3,200 MT/s, suggests a 2,000 MT/s ceiling for the V7 QLC. Since there is an OEM TLC-based drive in between the 990 EVO and 990 EVO Plus (the PM9C1a) at 2,000 MT/s, the possibility for a ~6 GB/s 990 or 990 QVO with V7 QLC existed.

Before we dive more deeply into the flash, since we haven’t seen the new Samsung QLC in a while and there is some neat tech here, let’s decode the module. “K9” tells us it’s Samsung NAND flash memory. “YYG” indicates it’s a QLC flash package with sixteen dies (HDP) in a 2TB configuration, which confirms 1Tb dies. “Y8” means it’s 8-bit, J tells us the voltage, “5” tells us the number of chips enabled and ready/busy signals, and “D” tells us the generation. With V7 being “C” and V8 skipped, this suggests V9. The second part of the code tells us how the flash is packaged and that it’s commercial / consumer-grade. While you aren’t expected to know how to read codes on your SSD, knowing how it works can be useful, especially with Samsung drives, even if it’s just a matter of trying to figure out if you have a counterfeit product.

So let’s talk about the flash. This is a 286-Layer part, technically, but is sold as 280-Layer once accounting for source/ground and dummy lines. Dummy lines are usually at stack edges, as the physics of flash can make these lines otherwise unusable. A higher layer count – Samsung’s V7 is only 176-Layer, although technically 191 layers – generally means higher bit density. Bit density is key to scaling NAND flash, which is acting as capacious, non-volatile storage media. This can be disappointing to some because it means you don’t always see any real performance scaling as the layer count progresses.

Fitting more flash into the same space can mean less room for charge in each cell, which makes it harder to optimize for performance if you’re trying to maintain the same endurance level. That is certainly the case with this flash, as the performance only manages to match that of last-generation 176-Layer QLC flash from competitors, which is why we want to go out of our way to point out Samsung’s design decisions and why it leans innovative in ways you won’t see in, say, your game load times.

For one, when we talk about the layer count difference – reported versus actual – you also get an efficiency number that is the ratio between usable and total word lines. Samsung is a leader here, with high layer efficiency. Samsung also has held off using three decks or stacks of flash and is still at two, due to having superior channel etching – it’s able to drill down more layers with a higher aspect ratio. It’s also possible to run lines through the flash itself rather than rely largely on masked steps, which sets the stage for Samsung scaling to extremely high layer counts. One issue with high layer counts is that you start losing uniformity from layer to layer, and Samsung accounts for this with optimized word line spacing, too. So, as we’ve said in the past, it often feels like Samsung is falling behind on layer count, but in reality it has a very focused strategy and the best technology in the business, and we can see this with the 990’s flash.

For the consumer, though, the 990 is a little bit weird. This is presumably 3,200 MT/s flash that is being “wasted” with a 2,400 MT/s controller. This flash has amazing bit density, but having a single sixteen-die package at 2TB is nothing new. What about performance? Samsung has made optimizations to improve performance on this flash, but nothing amazing. This QLC is only comparable to the competition in performance terms, particularly at 2,400 MT/s. Samsung is playing catch-up, but we also think this is a case of designing for enterprise rather than consumer.

QLC flash is now highly sought after in enterprise for its density, and Samsung’s optimizations all benefit that kind of environment. In fact, from a consumer’s perspective you could look at this V9 QLC as being focused on higher bit density – but no 2Tb dies – and you would largely be correct. Samsung’s V9 QLC is 86% more dense generationally and about 94% more dense than the competition’s 176-Layer QLC flash.

We’ll take a look at one new technology in the V9 QLC flash to illustrate. One important consideration is flash power interruption leading to data loss, which, without power loss protection (PLP) means you are looking at protecting data at rest. This is on the non-volatile media or flash, not the volatile memory like DRAM. When folding from the pSLC cache to the native flash, data loss is not an issue because you don’t invalidate the original pSLC copy until the write has been verified. However, when writing to native QLC, you are writing multiple pages where the upper pages will require higher levels of sensitivity for proper reading. There are different methods of writing to QLC flash, but generally multi-bit flash has multiple write passes that go from fuzzy (coarse) to precise (fine), and lower pages write faster and may be complete first. Therefore, it’s important not to ruin existing lower-page data if you lose power while still adjusting voltage for the upper pages.

Micron has a unique way of dealing with this using a differential engine that can predict values from partial shifts, but a more common method is simply to back up or buffer the values in nonvolatile flash. QLC stores four bits per cell, so a full backup means writing four bits of pSLC per cell. pSLC is used because its writes are fast, whereas QLC’s upper-page writes, in particular, are an order of magnitude slower. Samsung reduces the buffer to a single parity bit by using an odd/even algorithm, creating a sensing window that’s more like TLC (8-state) than QLC (16-state). This improves performance, endurance, and bit density. Some of that performance is still lost for higher bit density. For consumers, the direct benefit is higher TBW, but we speculate the higher density is aimed more at enterprise and future flash generation products. This is in part a response to Solidigm’s floating-gate design, a different technology than charge trap, with tighter charge placement.

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Comparison Products

The Samsung 990 enters a crowded market with a lot of good options, at least in theory. If we’re looking at QLC-based drives, this means the Crucial P310 and Sandisk WD Blue SN5100 at the very top. Both of these drives perform incredibly well. Below that, we have the older wave of drives represented by the TeamGroup MP44Q. That drive in particular remains a budget favorite with a fast controller and good QLC flash.

We would put the rest below that, even though the hardware is not always worse. This would include the Biwin M350, the Kingston NV3, and the Seagate FireCuda X1070. These drives are using alternative controllers – SMI, SMI, and TenaFe, respectively – that are roughly comparable, and the flash is not particularly old, either. However, these drives tend to be more budget-focused with reduced performance and (ideally) reduced cost.

We’ve also thrown in Samsung’s 990 EVO and 990 EVO Plus for comparison. The 990 should be closer to the latter, but with QLC flash, it would be okay landing somewhere in between. On the whole, we would expect the drive also to be between the two main categories of drives – that is, above the budget ones, below the two fastest, and closer to the middle MP44Q and its MAP1602-equipped alternatives, but with Samsung’s name recognition. The technology is here to make this a reliable drive, which is also a factor to consider, but being this late to the game puts the 990 at a general disadvantage.

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 an evaluation for future-proofing is included where applicable.

We start by looking at 3DMark because, frankly, QLC-based drives make a lot of sense for gaming. Aside from large installs and updates, you’re mostly doing reads, which do not favor TLC drives as much. While it’s true that QLC flash is still slower, often-accessed data might be left in the pSLC cache – if you leave enough space free – and QLC is also optimized for random reads. Games do involve a lot of sequential reads and often at larger block sizes than you’d expect, but as long as the drive has sufficient interleaving (it’s sufficiently large) you are going to get pretty good performance.

For 3DMark, which is a synthetic test, we might expect the drives to perform as they do under ideal, cached circumstances. This means the 990 should perform closely to the 990 EVO Plus and better than the 990 EVO, even though both of those latter two are TLC-based. It does. The 990 gets pretty close to the P310, which is one of the best QLC drives out there, aside from the Blue SN5100. We tend to look at ~45µs as a good cutoff point for all-around performance – gaming doesn’t need to be super responsive – which is roughly around the popular budget NV3. The 990 is significantly faster than that, which is all you could ask for here.

Trace Testing — PCMark 10 Storage Benchmark

PCMark 10 is an industry standard 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.

PCMark 10 performance usually, but not always, follows 3DMark. There is speculation that some drives or firmware may be optimized for benchmarks like PCMark 10, but taken within a greater suite of tests it’s still useful to get a feel for application performance. For us, that means for a primary drive – your boot or OS drive where your apps live – or for your everything drive, if you work and game on a single drive in your system. This isn’t too unusual with laptops where M.2 slots are limited.

The 990 again ends up roughly where we’d expect – above the 990 EVO, and close to the 990 EVO Plus. It’s not on the level of the P310 or Blue SN5100, but it’s clearly above the budget drives. This is a strong result with good latency. For instance, we would take the 990 over the NV3 any day, every day. On the other hand, the P310 and Blue SN5100 are frankly better drives. These two drives are better optimized and performance-oriented. The 990 is more of a gap filler that’s late to the scene.

We have to say, though, that we’re glad Samsung didn’t push out a 990 QVO that was more like the 990 EVO, even if it would have arrived earlier. Such a drive would have used older QLC flash and performed more slowly simply due to the lower interface speed.And frankly we’d rather have density-optimized flash that can run at the 990 EVO Plus level. That’s what the 990 delivers, even if it feels a little underwhelming. However, it makes perfect sense given the current market, enterprise demand, OEM demand, etc. The drive is still very fast and of a superior quality to a great many budget drives out there, and that makes it worthwhile.

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. Based on our extensive 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. 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.

You know our PlayStation 5 line by now: just about any drive will do. The 990 can push more bandwidth than the 990 EVO, which arguably makes it a better pick. It’s on par with, or better than, most budget drives out there. At least, for the things you will usually be doing on the PS5. It’s clear from our one bandwidth test that the drive ran out of cache, and it has the typical slow QLC flash write state. This is not indicative of real-world performance if you do normal installs/updates with mostly reads. If you are freshly installing the drive and moving a ton of games onto it, then yes, this could be an issue, but the QLC write speeds are still significantly faster than 1GbE if you’re intending only to download a ton of games at once. Otherwise, you can check the cache size in the relevant testing section.

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.

We also see some write performance issues in DiskBench. This is dependent on cache size and speed, but for the most part should be limited by the interface speed. However, there are cases where copy speed will simply be slower, whether due to the controller or other optimization trade-offs. We can see that the 990 EVO, with TLC flash, is not exactly doing great here, and the 990 EVO Plus does much better. However, the 990 lags behind, and is very far behind the P310 and Blue SN5100.

So, we can put some of this slow speed on the Piccolo/PiccoloQ controller. To avoid getting too technical on this, we suspect it is partially architectural. This is reflected in power efficiency, as both the P310 and Blue SN5100 – with the Phison E27T and a proprietary Sandisk controller, respectively – are significantly more power-efficient than the 990 EVO, 990 EVO Plus, and as we’ll discover, the 990 as well. We also know that Samsung’s V9 QLC flash is not particularly inefficient.

As for the controller, there are reasons to design it differently. Reliability is one reason, especially if you sell a lot of OEM and enterprise drives that share the technology. Scaling is another, as you may use similar technology across your stack. You might want to optimize for a different sort of performance baseline; you may have unique endurance requirements, and you also might have to keep capacity in mind – enterprise drives, in particular, could make better use of this flash’s interface speed when scaling for capacity. Therefore, DiskBench results for our specific testing may not really be what Samsung is optimizing for, in which case the 990’s performance more or less hits expectations based on the 990 EVO and 990 EVO Plus. It just disappoints against drives like the NV3, which are otherwise inferior.

And to put a cap on it, yes, this is a consumer drive, but if you go back and read our 990 EVO review – and other recent Samsung SSD reviews, for that matter – you will see we underlined the idea that Samsung has been late to the party with less-than-leading performance recently. The fact is, Samsung has and has had bigger fish to fry, and its technology is sound but no longer looks amazing on the standard consumer benchmarks. That makes its products less relevant if you just want the fastest drive, although we’d argue there are secondary effects like drive reliability that still keep Samsung in the fight, certainly as an OEM option. It’s also true that consumer use has a lower bar – any halfway-decent NVMe drive is fast enough for daily driving – which means, sometimes you’re just buying the Samsung name.

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.

ATTO gives us a clear image of how a drive performs over a range of block sizes. This can relate to different file sizes, for example, you probably have many files at or below 4KiB in size for various things but larger files, archives, and media files will usually be in units of MiB. Depending on what you’re using the drive for you may want to pay attention to how a drive performs within a certain range. For the quickest comparison, we show the results on a logarithmic scale and, there, the 990 shows significant dips for reads between 64KiB and 1MiB.

What you need to know is that flash is interleaved to improve performance, which means that larger I/O sizes will show higher throughput. A single, four-plane die, with modern 16KiB pages, can interleave up to 64KiB internally. If you have one die per each of four channels, that’s 256KiB. If you parallelize that over four dies per channel – which is the ideal amount and what we have with the 2TB 990 – then you reach 1MiB. While alignment here can impact performance, for example we sometimes look at six-plane flash these days, in general you will see a gradual throughput increase as you go. You’ll see this beyond 1MiB as data can and will be cached in volatile memory, either system-side or in a small cache on the drive. If you’re looking at higher queue depths, which we do with CrystalDiskMark, performance saturates even further as the controller is able to optimize data placement and retrieval with knowledge of what’s coming.

What this usually means is that QD8 is enough to get drives close together, while there will be more disparity at QD1. QD1 is much closer to real-world, as most operations will be at low queue depth, the vast majority at our below QD4 and the majority at QD1 or QD2.

We see that the 990 matches the P310 with QD1 reads, while some drives, like the X1070, do surprisingly well. We can assume that the controller plays at least a partial role here. The X1070 is a good example because, let’s be real, it’s not a drive a lot of reviewers liked. Yet, it has pretty good performance in this instance, indicating it could be a solid secondary storage drive. Fair enough. The 990 just doesn’t really have the response we like to see for that, but it’s fast enough to remain relevant. We got the impression in our X1070 review that its controller was chosen for cost savings and that was plenty for daily use, but we don’t think Samsung cheaped out on the PiccoloQ. Rather, Samsung is looking at the bigger picture, as it also sells drives with the Piccolo controller, including its OEM offerings.

Random latency seems much more important to a lot of people. We generally find that sub-50µs is one bar and another is sub-45µs. The 990 manages the former, which puts it above last-gen drives and some earlier Gen 4 drives, and budget drives like the X1070. It’s in the same ballpark as the NV3, too. It’s sufficiently far behind more popular budget drives, though, to draw our interest. In most cases you won’t notice it, but if you’re using this as your only drive and are sensitive to that, it’s not your best option. On the other hand, we think you have to balance that against pricing and some management of expectations. Any modern SSD is going to be very fast, and with current pricing it might be worth putting more weight on reliability, for example.

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, 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 15 minutes 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 including the steady state write performance.

Samsung’s TurboWrite 2.0 caching technology utilizes a fixed, static portion of pSLC combined with a much larger dynamic portion. These two zones have unique characteristics which, when taken together, ideally keep the drive feeling fast across a variety of workloads. The static portion ensures the drive always has some cache for random writes, while the dynamic portion varies with drive usage so that you always have ample cache. While the 990 EVO had 108GB total regardless of capacity, it’s more typical for Samsung to increase both caches in absolute terms as capacity goes up. This is the case with the 990 EVO Plus, which has a 216GB cache at 2TB. But we know from our 9100 Pro review that Samsung is quite capable of going with a larger cache. The general trend for consumer SSDs has been to go that way, especially for QLC-based and DRAM-less SSDs, as it better hides weak performance states.

Therefore, it’s not too surprising that the 990’s cache is pretty large. In its fastest state, it writes at almost 6.1 GB/s for over 57 seconds, for a cache in excess of 350GB. This is larger than the 2TB 990 EVO Plus’s but smaller than the 2TB 9100 Pro’s. Our suspicion is that the 990 follows the newer, larger scheme, but we’re dealing with QLC rather than TLC flash. QLC flash to pSLC is 4 bits to 1, while TLC is 3 bits to 1, so in relative terms the 990 lines up with the 9100 Pro. That’s all fine and good. As for how fast it writes, Samsung markets the 990 as having over 50% faster write performance than the 990 EVO, which is accurate simply because we’re moving from 1,600 to 2,400 MT/s, with newer flash and firmware.

Once the cache is exhausted, the drive has to write to the native QLC flash directly or fold data over from pSLC to QLC. The latter is slower but can reduce wear in some cases – folding uses predictable, sequential writes – and reduces the likelihood of errors in transmission. Considering the technology we mentioned above and how Samsung avoids problems with power loss, it makes sense that going slower is by design. In fact, given we know the expected speed of the flash – rated at 41 MB/s per die – we can reasonably assume the firmware wants this outcome. It’s not that the flash can’t handle higher speeds, even at the risk of endurance. It’s simply that for a consumer drive of this type, the response is reasonable and measured. Going faster would require reducing the cache size potentially, which tends not to be a good trade-off for this type of drive.

One interesting thing about the V9 flash is that it can operate in a pTLC caching mode. We don’t see that here. Honestly, that’s not too surprising: Solidigm’s 5-bit PLC flash effectively was designed to run as QLC/pQLC for enterprise, so it’s possible this pTLC mode was for cases where you might need that higher level of performance or endurance. After all, this is extremely dense flash even in such a mode, which points more at enterprise use.

We’ve seen QLC flash from Kioxia also optionally have this mode – and for that matter, Solidigm’s PLC can do pTLC, too – in the past, but that mode doesn’t appear to be designed for consumer use. There may be other reasons for not using it in a consumer product, such as power optimization, as consumer workloads probably benefit more from a straight pSLC and native/QLC hybrid.

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 in terms of capacity and performance. Desktops are often more performance-oriented with less support for power-saving features so we show the worst-case for idle.

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 but real-world temperatures will vary due to the environment and workload factors.

Is the 990 power-efficient? Samsung markets the drive as being 38% more efficient than the 990 EVO – or that it cuts power consumption by 38% – which, technically, works with our numbers. It’s not a huge bar to hit as the 990 EVO was not very power-efficient. Even the X1070 is significantly more efficient! The 990, unfortunately, really doesn’t do well against other drives in its class, regardless of flash. We can’t chalk this up as being fully due to the controller because the 990 EVO Plus does well enough for itself.

This is actually expected since, for example, the Blue SN5100, which is using BiCS8 QLC, is less efficient than its BiCS8 TLC sibling, the Black SN7100. QLC and TLC flash of the same generation often have significant differences. TLC flash saw six planes first while QLC tends to be optimized for density. While it’s true that pSLC performance between the two is often comparable, behind the scenes the drive still has to deal with wear-leveling, garbage collection, and other maintenance with block granularity. QLC is slower, with larger blocks and pSLC taking more bits. So all else being equal, TLC often outshines it in power efficiency.

Our impression here, as is the case elsewhere in the review, is that this flash is basically V7 QLC with twice the density. Samsung uses impressive tricks to get it there; the flash is technically a bit faster and more efficient, and it has some neat changes that mostly apply to enterprise. This means you can have the 990 doing worse than the 990 EVO Plus with its V8 TLC. This is not perplexing. QLC flash is made for bit density, and Samsung intends to scale flash for a very long time. It also skipped V8 QLC for a reason. This doesn’t endear it to people wanting to buy this drive for laptops, although we assure you that this does use some cutting-edge technology, and we do think it should be very reliable. It’s just not going to be as efficient as you might expect.

Samsung is cognizant that its drives will end up with OEM variants in laptops and in many cases, shorter form factors. The 990 EVO wasn’t a great laptop drive due to its heat generation, but it works. The 990 is significantly better, so it, too, will work as a laptop drive. We think this drive deserves a heatsink in a desktop or PS5, and probably should have heatspreading of some sort anywhere else, if at all possible.

The question is, will it overheat? In our testing, we found that it got closer than we prefer to that point. Our maximum reported controller temperature was high relative to the initial throttling temperature, but a true composite value would be lower. Even so, the controller did get warm. On the other hand, our Iometer testing is far from real-world. We push our drives hard. This is not the sort of drive for a desktop replacement or high-end laptop in our opinion, although we think with typical workloads it’s perfectly fine. After all, the results here are better than the SK hynix Gold P31, which is a laptop staple. By all means, in a Gen 3 slot this thing will fly. If you’re hammering it at Gen 4 speeds, though, yeah, it’s not the coolest drive in town.

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.

Samsung 990 Bottom Line

The Samsung 990 is bound to be underwhelming for some, but none of our results should surprise. We know what this technology is and we’ve seen Samsung’s entries in recent years with the 990 EVO, the 990 EVO Plus, and the 9100 Pro. You could even put the 980 and 990 Pros into that mix. The move away from DRAM on the EVO Plus series, in particular, was a sign of the times. It’s not surprising to see the raw 990 – the 980 was TLC-based – go to QLC without the “QVO” addendum. The original speculation of the 990 QVO being a QLC 990 EVO, with the EVO itself being a surprisingly “slow” drive, was probably correct given the OEM evidence, and the 990 being a step up lets it command the 990 name by itself. To reiterate, this is exactly what we expected.

Skipping over the 990 QVO and V7 QLC flash is only sidestepping, and that’s likely because the market has changed so much over the last year or two. Bringing out a QLC-based 990 EVO equivalent just wouldn’t sell and might even make the brand look bad. It could certainly be done, and even still done, as an affordable SKU with better yields. But any 990 was going to be exactly what we got, instead. You need the faster flash to saturate PCIe 4.0 with a DRAM-less drive, and this was always going to be DRAM-less. Using a new or licensed controller with TLC flash would be weird, as it’d be going up against the existing 990 EVO Plus. Frankly, the 990 is a good 990 EVO replacement from retail and OEM perspectives, with one caveat: endurance. Samsung saves itself some headaches by reducing the warranty to three years, and as this flash is robust, it can just nudge up the TBW as a distraction.

We think that’s an important part of the message here. This flash seems designed for enterprise and has technological changes to back that up, with the main consumer benefits being the potential for increased reliability. But memory is still in high demand, and this has to be a budget part, so here comes the three-year warranty. Performance is not bad – it certainly beats earlier Gen 4 QLC-based drives and would beat the rumored 990 QVO as well. It’s just not really performance-focused. It’s also a much more efficient design, but that’s in comparison to Samsung’s own hardware. It’s merely mediocre there in the current landscape. Samsung seems to be building for the future with higher layer counts and bit density, so this lays the groundwork. A client drive seems almost like an afterthought. Users shouldn’t take that personally, but also shouldn’t underestimate this drive as it’s more than effective enough for its purpose.

In fact, in the era of Gen 3 drives returning and so many “box of chocolates” SSDs with random names and hardware, a reliable Samsung SSD is a nice option. Even with QLC flash. If you only need a budget drive to throw into a build or to upgrade an old PC, you get Gen 4 performance and a TLC-like experience for most things. We also feel this drive should be reliable and, although it runs hotter than we’d like, it’s not going to be molten like some other drives. It’s just a polished design by Samsung that fills a micro niche, and clearly it thought a response was needed. It’s not a lot different than our reaction has been to Samsung’s last few new drives, which have all been competent but largely never the strtong leader. That’s okay with us, as we can tell the manufacturer has a longer-term perspective; it just means a little less awe when you finish a build using a Samsung drive.

If you really want the best experience with a QLC-based drive, we still recommend the Crucial P310 – which is going away – or the Sandisk WD Blue SN5100. These offer incredible performance for QLC flash. Otherwise, there are some MP44Q-like drives out there that continue to be budget leaders. The 990 fits somewhere along there as a known-brand alternative. If you’re looking for Gen 5, DRAM, or TLC, then you’re also looking at a higher price tag. Frankly, QLC costs more than it should, in part due to enterprise demand. On the other hand, a modern QLC drive will provide an equivalent experience 99% of the time. The priorities are up to you. For us, the 990 is a fine primary drive for normal builds and OK for laptops, although we’d go cheaper for the PS5 and higher-end for an enthusiast machine.

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