Samsung SM951 (512GB) PCIe SSD Review
by Kristian Vättö on February 24, 2015 8:00 AM ESTFinal Words
When the news that the SM951 isn't NVMe enabled hit the Internet, there was a lot of disappointment around. Understandably many were expecting that the SM951 would merely be an evolutionary step from the XP941 because AHCI command set would still limit the full potential of the PCIe interface, but Samsung proved us all wrong. The SM951 is far from being a marginal step up from the XP941 because in most of our tests the SM951 beats the XP941 by a 50-100% margin. As a matter of fact, the upgrade from XP941 to SM951 is bigger than going from a SATA 6Gbps SSD to the XP941. Despite the lack of NVMe, there's no arguing about the fact that the SM951 is the fastest client SSD and by a very healthy margin.
From a performance perspective I have absolutely no complaints aside from thermal throttling. I wouldn't consider it to be a major issue because regardless of some throttling in synthetic tests, the SM951 is easily the highest performing drive. The Destroyer test takes about 10 hours to run on modern drives, so if throttling was a real issue it would show up more clearly in the results too. Besides, my half-open testbed isn't ideal for airflow either, but since I haven't encountered noticeable throttling in the past I wanted to mention it in case anyone runs into performance issues with the drive.
Right now the biggest issue with the drive is its nearly nonexistent availability, though. If you want to get your hands on the drive today, the only known way to do that is to buy Lenovo's ThinkPad X1 Carbon that is configured with a PCIe SSD. The cheapest configuration with a 512GB SM951 comes in at $1,709.10, so there's practically no sane way to get access to the drive (unless, of course, you want the X1 Carbon laptop as well and are willing to pay the price).
That brings us to the next subject. Since retail availability isn't expected until late May at the earliest, there's a chance that the SM951 will no longer be the fastest SSD once it's actually available for purchase. At CES last month, several SSD vendors told me that they should have PCIe SSDs ready for Computex, which is in early June, i.e. right after the SM951 is scheduled to start shipping.
If the SM951 was available today, I would have no reason not to give it our "Recommended by AnandTech" award. Being hands down the fastest client SSD on the market is enough justification for the award, but because the drive won't be shipping for several months I can't be sure that I'm still recommending the SM951 once it's available. For now the only thing we can do is wait, but at least we can do it in peace by knowing that the future is quick and bright.
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Kristian Vättö - Wednesday, February 25, 2015 - link
I didn't test any OCZ drives for this review because the Vector 180 NDA is due in a couple of days, so stay tuned.IlikeSSD - Thursday, February 26, 2015 - link
Vertex 460A is good enough to show the difference (maybe even Arc))Shadowmaster625 - Wednesday, February 25, 2015 - link
You should clip on a simple heatsink and run the tests again.squatsh - Wednesday, February 25, 2015 - link
Based on the orientation of the drive in it's M2 slot. (Ie is the controller facing up or down) Can it be made clear if we could just put a small thermal pad and one of those tiny heatsinks (like you can get for VRMs) on the controller (assuming that is what is overheating) in order to stop the thermal throttling on desktops and laptops with enough space.Luke212 - Wednesday, February 25, 2015 - link
what happened to the Intel P3500? It's been a year and nothing.Mikemk - Wednesday, February 25, 2015 - link
Comment 100Sorry, couldn't resist
awall13 - Thursday, February 26, 2015 - link
Thanks for the great review. I like the changes in how the data is presented. One idea: In the performance consistency section, the steady-state performance could be presented with a single two-color bar per drive, with the full bar representing the average performance, and the shorter bar representing the average - 1 standard deviation. I'd still keep the second chart showing the standard deviation by itself, perhaps. Just a thought.gseguin - Thursday, February 26, 2015 - link
Performance performance performance. Ok, I get it, its fast and hard to find.Since we saw many issues crop up with the predecessors, with eventual fixes by Samsung, how much confidence is there in the drive itself from Anandtech... You know the controllers, you know the memory, you've covered different company's testing methodologies, how much confidence do you have in this product, and why is that absent from the introduction and final thoughts?
Kristian Vättö - Thursday, February 26, 2015 - link
All Samsung's issues have been related to SSD with planar TLC NAND (i.e. 840 & 840 EVO). There is absolutely no reason to believe that the SM951 shares the issues because it's based on MLC NAND and Samsung's MLC NAND based SSDs have been flawless (830 & 840 Pro).kgh00007 - Saturday, February 28, 2015 - link
Hey, nice article. I like the new SSD test suite. Is there any way to add a long term read consistency test, or any sort of read consistency test in light of the Samsung 840 EVO issues?I'm an 840 EVO user with drops in read speed to below 50Mb/s. In fact I have never gotten the advertised 500MB/s read speeds on any SSD I own. Is that because I am using them as the boot drive?
Do you test with the SSD as a second drive in the system? So taking out the overhead of the OS running on the drive as well as the test suite?
Cheers, keep up the good work, I've been learning from this site for a long time....