Silicon Motion SM2504XT Controller Review - Best DRAMless SSD Ever

TweakTown Rating: 100%

Our Verdict

Simply stated, this is the most impressive SSD we've ever encountered!

Pros

• Sequential throughput performance
• Real-world performance
• Power efficiency

Cons

• None

Should you buy it?

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Introduction & Drive Details

For more than a year now, we've been waiting for a 4-channel PCIe Gen5 DRAMless controller from Silicon Motion to land on our test bench. Having just returned from FMS 2025 and seeing first-hand what is coming soon in the world of solid-state storage and memory, we've had the good fortune to take back with us from the show an engineering sample of the SSD/Controller we've been dying to get our hands on most of all.

Silicon Motion's SM2504XT, like its predecessor, the SM2508, is architected on TSMC's 6nm process node, making the controller the most power-efficient in its class, and in the case of the SM2504XT, we have in hand what is likely the most power-efficient SSD controller ever made. Consuming only 2.4 watts in active mode, while delivering up to 11,500 MB/s throughput, the SM2504XT is in a class of its own.

The SM2504XT is set to do battle with the likes of Phison's well-established 4-channel, 7nm node E31T and Maxio's newly unveiled 8-channel MAP1802A DRAMless controllers. Having already taken both of those controllers for a spin, we don't see it as much of a contest as the SM2504XT is far more efficient and, when arrayed with the latest TLC flash, far more powerful where it matters most - real-world consumer applications.

Our 2TB SM2504XT engineering sample is an exact replication of a soon-coming retail SSD from a well-known manufacturer, so the performance numbers we will be presenting here today are identical to at least one retail SSD powered by the SM2504XT controller.

For a long time now, we've been waiting on a DRAMless SSD that can deliver TT 17K Elite performance. To date, nothing DRAMless has been able to get there, not even Corsair's E31T-controlled, BiCS 8 arrayed MP700 Elite has been able to achieve 17K Elite status. Today, that changes.

The SM2504XT engineering sample we have in hand smashes right through 17K Elite status and sets the new DRAMless performance bar at a mind-blowing 20K. 20K TT Elite from a DRAMless SSD? Yep, and all while consuming a mere 2.4 watts of power. This is efficiency on a higher level, and performance where performance matters most - so much so, that we not only need to up our TT Elite performance category from 17K to 19K, but we also need to rethink what we consider the all-around best SSD to be.

Simply stated, we are of the opinion that when taking all factors into consideration, the subject of today's review is indeed the SSD we can universally recommend over any other. In our considered opinion, there is nothing else we've encountered to date that compares to our test subject's performance-to-efficiency ratio. Nothing else is even close. This baby can outperform a whole host of full-on 8-channel controlled PCIe Gen5 SSDs with onboard DRAM and do so while consuming less than half the power.

Okay, now let's dive in and see what we consider to be the best SSD we've ever encountered can do by the numbers.

Drive Details

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Jon's Test System Specifications

Intel Test System

AMD Test System

Please note: We employ an M.2 AIC for testing on our Intel Core Ultra 9 285K platform.

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Sony PlayStation 5 - M.2 Storage Expansion

PS5 Read Performance

With Sony's wildly popular PlayStation 5 console now enabled for M.2 NVMe SSDs to be used as fast storage expansion, we are including results for PS5-compatible SSDs we test as a part of our reviews going forward.

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We only chart SSDs that can deliver a minimum of 5,500 MB/s read, which is Sony's original recommendation.

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We are of the opinion that with its unprecedented power efficiency, which translates directly to tame thermal characteristics, SM2504 XT controlled SSDs are ideally suited for PS5 storage expansion.

Synthetic Benchmarks: CDM, Max IOPS, ATTO

CrystalDiskMark

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We employ CDM as our standard measurement for both sequential throughput and Q1T1 random read. In terms of sequential throughput, the drive delivers extremely well, delivering more than a GB/s, better than the MP700 Elite. And while that is impressive in its own right, we are blown away by its QD1 random read performance of over 127 MB/s, which is the best synthetic indicator of real-world prowess.

Max IOPS

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The 2504XT controller is factory spec'd as capable of up to 1.7 million random read IOPS, and that's exactly what we are seeing here. Random write performance, we do not care about, as it is mostly irrelevant for consumer use case scenarios.

ATTO

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ATTO gives us a clear picture of what transfer sizes a particular SSD favors in terms of QD4 sequential throughput. We chart 128K transfers. At a queue depth of four, our 2TB test subject favors sequential transfers of 512KB or larger when serving data to the host (reading) and 128KB or larger when programming (writing) data.

Real-World Testing: Transfers, 3DMark SSD Gaming Test, PCM10 Storage

Transfer Rates

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Our 100GB data transfer test is not your ordinary 100GB of data; ours is a crushing mix composed of more than 62K files. Writing performance, random or sequential, is an infrequent operation and as such, we do not consider it to be an important performance metric in the consumer space. An example is how many times a game is installed vs. how many times it's played. Plenty good enough for our liking.

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Unlike programming (writing) data, serving data to the host (reading) is typically an important performance metric as it relates to the consumer space. This is where transfer rates matter most, and we like what we see from our test subject, where we again find it outperforming its DRAMless direct competitor by a whopping 1 GB/s. Excellent.

3DMark SSD Gaming Test

UL's newest 3DMark SSD Gaming Test is the most comprehensive SSD gaming test ever devised. We consider it superior to testing against games themselves because, as a trace, it is much more consistent than variations that will occur between runs on the actual game itself. This test is the same as running the actual game, just without the inconsistencies inherent to application testing. In short, we believe that this is the world's best way to test an SSDs gaming prowess and accurately compare it against competing SSDs. The 3DMark SSD Gaming Test measures and scores the following:

• Loading Battlefield V from launch to the main menu.
• Loading Call of Duty Black Ops 4 from launch to the main menu.
• Loading Overwatch from launch to the main menu.
• Recording a 1080p gameplay video at 60 FPS with OBS (Open Broadcaster Software) while playing Overwatch.
• Installing The Outer Worlds from the Epic Games Launcher.
• Saving game progress in The Outer Worlds.
• Copying the Steam folder for Counter-Strike Global Offensive from an external SSD to the system drive.

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Gaming is a performance metric that matters to most DIY consumers, especially for the enthusiast crowd that TweakTown caters to. Now we've reached the point where results start to matter as they are a direct reflection of user experience.

Here we find our competitor delivering the most ever gaming performance for a DRAMless SSD. You want the most performance where it matters most? This drive can deliver just that. This is a top ten all-time performance coming from a 4-channel DRAMless SSD. This is unprecedented.

PCM10 Storage Tests

PCMark 10 Storage Test is the most advanced and most accurate real-world consumer storage test ever made. There are four different tests you can choose from; we run two of them. The Full System Drive Benchmark and the Quick System Drive Benchmark. The Full System Drive Benchmark writes 204 GB of data over the duration of the test. These tests directly correlate with mainstream user experience.

PCMark 10 Full System Drive Benchmark

This test writes 204GB of data and covers a broad range of common consumer tasks, including booting Windows 10, file transfers, Adobe and Office applications, and startup times for games such as Battlefield V, COD Black Ops 4, and Overwatch. Unlike synthetic numbers, this is comprehensive real-world data, which is why we use it to rank SSDs in terms of user experience.

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Traditionally, this is where DRAMless SSDs are brought to their knees, but not our test subject. Again, absolutely stunning real-world performance.

PCMark 10 Quick System Drive Benchmark

The Quick System Drive Benchmark writes 23 GB of data over the duration of the test.

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Of all the benchmarks we run, it can be argued that this one offers the best reflection of a typical consumer use case scenario. And as a parting shot, our little DRAMless wonder rounds out our testing session with another jaw dropper. This is performance on a higher level.

Final Thoughts

Well, it's been a long time coming. We finally have a DRAMless SSD without a single drawback. Not only has this SM2504XT reset the bar of what's possible with 4-channels and no DRAM, but it's also delivered a compelling argument for choosing DRAMless over conventional enthusiast configurations, even for those that are performance-first minded. Think about it. Half the channels, half the cost, half the heat, and twice as efficient as anything delivering similar real-world performance.

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We rank SSDs in terms of overall user experience (performance where it matters most) as expressed by PCMark 10 storage and 3DMark gaming storage tests. Currently, we consider a user experience score of 19K or more to verify an SSD as a TweakTown Elite performer. The engineering sample we tested today has compelled us to raise the bar from 17K to 19K to qualify as a TT Elite performer.

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As we see it, the SM2504XT controller is the most impressive controller we've ever encountered, and the 2TB engineering sample we tested today is our new favorite SSD. Editor's Choice.