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Review: Samsung 840 EVO 250GB mSATA SSD

Review: Samsung 840 EVO 250GB mSATA SSD

Sam ChenDecember 30, 2015

Same Great 840 EVO, Now in mSATA

samsung-840-evo-250gb-msata-custom-pc-review-5Several months ago at the 2013 Samsung Global SSD Summit, Samsung unveiled their latest and greatest SSD, the Samsung 840 EVO. Based off a brand new MEX controller and Samsung’s latest 19nm TLC Toggle Mode 2.0 NAND, it quickly became one of the most successful consumer SSDs on the market due to its great performance, competitive pricing, and proven Samsung reliability.

Now I’d have to say ever since the release of the Samsung 840 EVO back in July, I’ve been expecting a mSATA form factor version of the 840 EVO as well, at least on the OEM side of things. When I reviewed the 250GB edition of the Samsung 840 EVO, I noticed that it had a very small PCB, about the size of a mSATA SSD, with only two NAND packages onboard. Given that Samsung already produces a mSATA PM840 SSD based on the 840 Pro, it was logical that an 840 EVO based SSD in the mSATA form factor would arrive, especially since the SATA version’s PCB is already about the size of a mSATA SSD anyway.

Fast forward five months after the initial launch of the 840 EVO and Samsung is now launching the Samsung 840 EVO mSATA SSD. I expected Samsung to introduce a 120GB, 240GB, and 500GB mSATA 840 EVO, but what I didn’t expect was a 1TB edition as well. Whereas the 120GB, 250GB, and 500GB 840 EVOs used four NAND packages or less, the 750GB and 1TB editions used eight packages, which wouldn’t normally fit into a mSATA PCB. This means that Samsung has figured out a way to fit 1TB of data into four tiny little NAND packages. That’s very impressive and it could mean some serious capacities down the line with 8, or even 16 of these high density NAND packages on a full sized 2.5″ SATA PCB.

Samsung 840 EVO mSATA Specifications

Model840 EVO840 EVO840 EVO840 EVO
Capacity120 GB250 GB500 GB1000 GB (1TB)
ControllerSamsung MEXSamsung MEXSamsung MEXSamsung MEX
NAND19nm Samsung Toggle 2.0 TLC19nm Samsung Toggle 2.0 TLC19nm Samsung Toggle 2.0 TLC19nm Samsung Toggle 2.0 TLC
Sequential Reads540MB/s540MB/s540MB/s540MB/s
Sequential Writes520MB/s520MB/s520MB/s520MB/s
4K Random Read95,000 IOPS97,000 IOPS97,000 IOPS97,000 IOPS
4K Random Write37,000 IOPS71,000 IOPS88,000 IOPS88,000 IOPS
InterfaceSATA 3, 6GB/sSATA 3, 6GB/sSATA 3, 6GB/sSATA 3, 6GB/s
Warranty3 Years3 Years3 Years3 Years

From the specs, it looks like the Samsung 840 EVO mSATA is pretty much identical to the Samsung 840 EVO SATA. The 500GB/1TB editions will have the highest level of performance topping out at 540MB/s sequential reads and 520MB/s sequential writes with 4K reads/writes topping out at 97,000 and 88,000 IOPS respectively.

Our review today will be focused on the Samsung 840 EVO 250GB mSATA SSD. The Samsung 840 EVO 250GB mSATA is rated at up to 540MB/s sequential reads and 520MB/s sequential writes, which is identical to the maximum sequential read/write performance on the 500GB and 1TB models, but it does suffer a bit in 4K write performance, dropping to a maximum of 71,000 IOPS. In order to reach these lofty performance numbers on slower, more error prone 19nm 128Gb TLC NAND, Samsung is implementing TurboWrite technology, which we’ve covered in our review of the SATA based Samsung 840 EVO.

Let’s take a closer look!

About The Author
Sam Chen
Hardware and Technology Enthusiast. SSD Evangelist. Editor-in-Chief. You can find Sam's full biography here
  • Michal Wiktorow

    Still, this review lacks stressing out how much is lost after transition to TLC, sometimes writes on EVO after 3TB Host Writes and in used state are only 80MB/s. That is not what people expect from SSD. If you need SSD, look at 840 PRO or other device with MLC NAND.

    • The reason I don’t stress this is because the Samsung 840 EVO is a consumer grade drive and for most users (even enthusiasts such as myself) it’s rare to need to put 3TB of writes in without any breaks to allow the TurboWrite cache to flush itself. Sure I do it when I install a game or something, but I don’t really spend all day downloading and installing stuff. For those moments, I can just wait for it to install at 275MB/s. No big deal.

      That said, you’re right. There is a huge loss in write performance and latency moving from MLC to TLC, but you’re looking at the difference between like ~470 MB/s to about ~250 MB/s (assuming you’re talking about large file transfers here, 128K or above). Sure I’ve seen the 840 EVO drop as low as 80MB/s or 30MB/s, but that requires you to fill up all LBAs, fill up TurboWrite AND not give TurboWrite or TRIM a chance to restore performance. Unless you’re benchmarking like I am, running a server, or doing some sort of enterprise work, I simply don’t see that happening in any typical client use scenario. If that’s the case, even the Samsung 840 Pro isn’t recommended. A enterprise SSD is what you want instead.

      For client use, I think the only real case I’ve come across for a Samsung 840 Pro over a EVO is for those doing real-time video recording of one or multiple uncompressed video streams. Recording as in somebody had a couple capture cards to record gaming footage from a couple other computers. In that case, yeah the ~470MB/s from the 840 Pro is much better than the ~275 MB/s off the 840 EVO after TurboWrite. However, after TurboWrite you still get ~275MB/s-270MB/s (from my testing although Samsung rates ~250MB/s) so as long as footage is compressed, I don’t see much of an issue from a performance standpoint. That said, for those doing any sort of video, photo or 3D work I recommend the 840 Pro anyway just because its longer warranty and endurance.

  • Ed

    what we really want is pcie drivers or m2 with MLC maybe an EVO5 PRO in 2014?

    • Yup. I agree. I think it’s just time for motherboard vendors to start implementing SATA Express/M.2 into their designs. I believe NVMe drivers are already available in both Linux and Windows 8.1, so the “infrastructure” is already there.

      For sure I wouldn’t be surprised to see a Samsung 850 Pro/EVO come in M.2 or SATA Express come July next year. They already have a M.2 XP941 that’s shipping in some OEM solutions. They just don’t want to ship to end users since there’s no widespread way for us to use it yet.