The Samsung 950 Pro PCIe SSD Review (256GB and 512GB)
by Billy Tallis on October 22, 2015 10:55 AM ESTFinal Words
Testing of Samsung's 950 Pro revealed some curiosities. Nevetheless, even when showing symptoms of possible thermal throttling, the 512GB sustained respectable performance and in tests that were representative of interactive use it performed extremely well. Users waiting on a full range of Skylake systems to come to the market may need a PCIe to M.2 adapter in order to put the drive in a slot that provides four lanes at PCIe 3.0 speed, but with the added benefit that such adapters can be bought with heatsinks to reduce the chance of triggering thermal throttling.
It's hard to judge pricing when there are limited options in this market segment. The Intel SSD 750 clearly needs to come down in price to be completely sidelined by the 950 Pro. Comparing against SATA drives, the 950 Pro's impressively high scores seem to make a good case for its price premium, but consider how often a particular use case will actually be able to take advantage of the peak speeds offered, which makes the 950 Pro a more prosumer oriented product. The 950 Pro isn't for everyone, and if cost is a sensitive issue then the 950 Pro should be weighed against Samsung's other offerings. But simply for a top of the line drive, the 950 Pro is priced reasonably for enthusiasts.
As a sign of where the SSD market is going, the 950 Pro clearly shows that SSD performance can be improved. Before too long, "high-end SATA SSD" will be an oxymoron; it's time for the transition to PCIe! The transition to NVMe seems less urgent given what Samsung was able to do with the SM951 and XP941 using AHCI, especially due to compatibility and drivers at this time. The power management issues in particular will need to be taken care of before NVMe moves beyond the enthusiast segment, especially for mobile computing.
The PCIe 3.0 x4 interface certainly gives the drive plenty of headroom. And based on the performance of the 950 Pro, it's doubtful that an M.2 drive will be able to saturate the interface before running in to thermal limits while still remaining in the same form factor. Future drives in this area will probably have to implement aggressive power saving techniques in order to keep average temperatures low enough to accommodate bursts of activity. The 950 Pro and the PCIe ecosystem in general have a lot to improve upon here.
The M.2 form factor is also constraining drive capacities to a degree. The back side of the 950 Pro is empty so a 1TB model should be geometrically possible if not economical, but the extra NAND packages would be even more susceptible to thermal problems. Samsung is instead choosing to wait for their 256Gb third-generation V-NAND before offering a larger model of the 950 Pro.
So far, Intel is the only manufacturer that has produced an enthusiast drive using the U.2 connector to provide PCIe x4 to a 2.5" drives. U.2 support is far less common than M.2, but the next time Samsung wants to introduce a major performance boost, they may go for the 2.5" U.2 option. We have already seen U.2 connectors directly on a pair of ASUS motherboards announced this week, and a number of Skylake consumer motherboards will come with M.2 to U.2 adapters specifically for this purpose.
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Billy Tallis - Thursday, October 22, 2015 - link
If I'd had more time, I probably would have done more informal testing on some older machines. I can at least assure you that the drive doesn't seem to have any trouble in a PCIe 2.0 x2 M.2 slot on my personal Haswell machine. Next time I'm poking around in my Lynnfield server I'll be checking how the pcie drives work, especially power management. But I probably won't do a full suite of performance tests, just enough to get a rough idea for how fast drives perform on a slower link. And I really don't have a clue when I'll get around to this, because I've still got quite the backlog of drives to review.hansmuff - Thursday, October 22, 2015 - link
Understandable, thanks for the PCIe 2.0 update.The_Assimilator - Thursday, October 22, 2015 - link
Thermal throttling is disappointing but shows that M.2, like SATA Express, is DOA. PCIe drives with heatsinks, or preferably U.2, is the future - hopefully with the Z200 series chipsets, manufacturers will ditch SATAe in favour of U.2 and we can finally get a worthy successor to SATA3.MrSpadge - Thursday, October 22, 2015 - link
DOA it certainly is not. You're free to attach a tiny RAM heatsink on the drive and be fine. Or simply forget about throtteling in real world usage (unless you use it in a server).Redstorm - Thursday, October 22, 2015 - link
Under a normal client workload you don't get anywhere near triggering the thermal protection so adding heat sinks is not required. Agree SATA Express was still born. M.2 is far from it, if you look at any new release ultrabook you will find a M.2 SSD under the lid.The_Assimilator - Friday, October 23, 2015 - link
M.2 is a great solution for replacing 2.5" SSDs in space-limited applications like ultrabooks, but for *absolute maximum performance without thermal throttling*, 2.5" U.2 drives a la Intel's 750 are still the way to go.zodiacfml - Sunday, October 25, 2015 - link
It depends on the designer on how much throttling they would allow or not. U.2 allows more freedom though but I reckon would be much more expensive and less dense in the future.user_5447 - Thursday, October 22, 2015 - link
Why everyone keep saying that BIOS/UEFI must support NVMe to boot into OS?You can install GRUB bootloader on cheap small USB flash drive and use it to boot from NVMe drives on any system, since GRUB itself supports NVMe for few years now.
And yes, GRUB supports booting into Windows 8.1 / 10.
bji - Thursday, October 22, 2015 - link
They say it because it's true. Nobody wants to have to manage a USB drive just for booting their system. You can also install a floppy drive and boot from that, would you recommend that also? How about keeping a separate computer up constantly to support PXE booting from the network? Would you recommend that level of headache to someone who just wants to boot their frickin computer?bji - Thursday, October 22, 2015 - link
By the way, of all of the things I have to deal with when installing/upgrading Linux systems, grub is the most painful and problematic, by MANY orders of magnitude. I would *NEVER* recommend that a non-technical user have anything to do with grub, especially not for something as silly as booting a PC into Windows off of an NVMe drive.