Before we delve in, we should note that our current SSD test motherboard (Asus Maximus V Extreme) does not have an M.2 port, nor do we have an adaptor. As such, to test the M.2 drive, we switched to a different test system, using the on-board port in a Gigabyte Z97X-UD5H with a Core i7-4790K. As such, this drive was tested on a newer platform and with a newer IRST driver than the rest. We've left it in the same charts for ease of reference, but it's not technically a direct comparison.
Click to enlarge
With that out the way, sequential performance is more or less the same as the 2.5in equivalents, with the supposedly slightly lower sequential performance of the M.2 drive not actually materialising. Even when this small, the SSD 850 EVO drives are some of the fastest around. Of course, this is burst performance, which takes advantage of TurboWrite, and sustained writes will see a sharp drop in performance. However, burst performance is very relevant to home users, so it's a good solution.
Single queue depth random performance shows the 1TB mSATA drive performing the same as the regular one for both reads and writes. However, the M.2 500GB is significantly faster, almost abnormally so, and achieves the best read and write speeds of any drives on test. Since the drive's hardware and interface are the same as the 2.5in one, this is more likely due to the updated test platform.
At high queue depths, the drives draw roughly level and cluster near the top of the charts, with just a few MB/sec separating the M.2, mSATA and 2.5in models.
Click to enlarge
As we saw, the M.2 drive has strong random performance, and this seems to benefit it in the PCMark 7 traces, which makes sense as there's a lot of random read and write activity in these workloads. Again, though, this is likely down to the updated test platform and drivers, as the 1TB mSATA model performs almost identically to its 2.5in brother.
The small form factor drives start strong in the Iometer mixed workloads, but fall to performance levels that's slightly below that of their 2.5in equivalents as the tests continue, although not drastically. The 12 hour consistency test again shows similar results to before i.e. nothing special, though the larger capacity drives take a little longer to reach steady state. Still, these are unlikely workloads for this class of SSD, so it's little to be concerned about.
Just as with the SSD 840 EVO, Samsung has successfully transitioned its mainstream SSD offering to smaller form factors with little to no impact on performance and features. Having so much storage available in so little space still impresses, and the mSATA drives are bound to appeal to fans of mini PCs like Intel's NUCs, while the M.2 ones will surely find a welcome home in Z97 and X99 motherboards that support them, especially form factor ones where the benefits are more obvious. For this reason, we would have liked to have seen a 1TB M.2 drive as well, even though it would mean going double-sided, but you can't have it all.
Click to enlarge
The pricing means that the drives carry a slight price premium over the 2.5in drives, but that's to be expected. At around 36p per formatted GB, the 1TB mSATA drive is in a very good position to take over from the SSD 840 EVO, simply because no other company has yet crammed this much capacity into this form factor – it's without competition. As for the 500GB M.2 drive, its retail price means it goes head to head with the Crucial MX200 500GB M.2. While we don't have performance figures for that drive, Samsung's superior feature set and endurance is hard to argue with. Faster M.2 drives are available i.e. those from Plextor and, soon, Kingston, that are PCI-E based and not limited by the SATA interface, but these are seriously expensive - £320 or more for the same capacity, for example – so are best left to serious storage enthusiasts. In short, if you need a high capacity mSATA or M.2 SSD, the SSD 850 EVO is a fantastic option, and we're awarding both drives here the same in reflection of this.