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Samsung SM951 512GB M.2 PCIe SSD Review

By: Chris Ramseyer | PCIe in Storage | Posted: Jan 30, 2015 2:42 pm
TweakTown Rating: 98%Manufacturer: RamCity

Final Thoughts




I'm going to show my age in this section. In nearly every game Quake manual Quad Damage is defined as "Magnum upgrade! You now deliver four times the pain!"


When you retrieved the blue Quad Damage orb, a voice would announce that you have QUAD DAMAGE! While testing the Samsung SM951, I kept hearing in my head the QUAD DAMAGE announcement. Maybe it's just the fact that the SM951 takes advantage of PCIe 3.0 x4, but something connected to this drive reminds me of 4x. While testing, I noticed a lot of 4x when compared to modern consumer SATA 6Gbps products.


With flash lithography shrinking in parallelism, SATA drives are actually getting slower outside of premium products. It's common to see large capacity value drives unable to meet the maximum write speeds available with SATA these days. The SM951 512GB doesn't have that problem and is able to deliver around four times the real-world performance of a value class SATA 6Gbps SSD. I would call that "Quad Damage".




It's not just that the Samsung SM951 is able to deliver high performance in corner cases. The low queue depth performance means you actually feel the performance increase. I noticed this right away when installing Windows 8.1 on the Lenovo X1 Carbon for the notebook battery test installation. I didn't have time to drink a cup of coffee, I barely had time to get a few sips in before I needed to start playing 20 questions with the operating system. If someone were to chart how long it takes to install Windows, I think I set a world record.


The performance isn't one sided. You get high write speeds that complement the high read speeds. We often find that SSDs are very good at reading data, but lack write performance. That isn't the case with the SM951 - it's a very balanced SSD.




Other PCIe based M.2 drives we've tested, including the XP941, lacked the balance and it came through in our mixed workload tests. In a real environment, you never just read data or write data. You are always mixing reads and writes. Some drives handle mixed workload better than others and those that do well in our test are also the same drives that feel fast in our systems. The synthetic benchmarks may show one drive running better at each of the four corners of performance, but over time, that drive feels sluggish. At the same time, a drive that performs average in the four corner tests, but does well at mixed workloads feels faster in real-world use.


There are a handful of trace based benchmarks that show real-world performance with mixed workloads. One of our favorites is PCMark Vantage. The test is older now and the software traces are no longer representative of Windows 8 traces. The software is still a solid measuring stick to compare SSD products, though. With SATA 6Gbps products, a reputable score is anything over 90,000 Marks - the Samsung SM951 gave us a score over 240K.


I've spent the last ten hours working on this review with the SM951 as the boot drive and I can say the drive is really that good. While writing, I listen to music, talk to team members over Skype, take breaks to surf Facebook and edit pictures down for publication. ALT+Tab is glued to my fingers and never has a system felt this snappy.


The only question left is how and when these drives will become available. At this time, your only outlet is Lenovo and only on the X1 Carbon G3. Dell stated the new XPS 13 (2015) will have an option for the SM951, but after looking at the Dell site and its options, we could only find a generic statement that lists a 256GB SSD. The Engadget review system from Dell used a SATA based M.2 SSD, so like Lenovo, we would like to see some clarification before spending that kind of money on a nameless storage product in a high-end Ultrabook.


In the coming months, will carry the SM951 in all three capacity sizes: 128GB, 256GB and 512GB. We suspect Samsung is still fulfilling orders for the OEM companies so there will be a delay from the time you read this till RamCity takes first delivery. The prices should be significantly less than the $700 Lenovo charges for a 512GB model.


When RamCity gets SM951 products in stock, we'll be able to test the drives and figure out the sequential performance rating. The Samsung documents state the maximum sequential read speed should be able 2150 MB/s. With the Lenovo drive, we only managed to get close to 1700 MB/s, even though use used the same test and same settings Samsung's documents show. If the Lenovo version is tamed to reduce power consumption, like we think it possibly is, it will be very interesting to see what an untamed SM951 is truly capable of - hopefully we don't have to wait very long to answer that question!

Product Summary Breakdown

TweakTown award
Quality including Design and Build98%
General Features97%
Bundle and PackagingN/A
Value for MoneyN/A
Overall TweakTown Rating98%

The Bottom Line: It's the fastest and the best consumer SSD ever made public. Performance takes on a new meaning with this drive because the mixed workload efficiency is so high.

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