Samsung 850 EVO 500GB

The Samsung 850 EVO is the latest in its affordable line of performance SSDs and shows Samsung's desire to push the solid state game along, even at the lower end of the price/performance stack.

When it comes to solid state drives Samsung has really nailed its colours to the mast; it's going to be first to market with new technologies, it's going to aggressively drive pricing down and it's going to do it all alone.

To that end, the Samsung 850 Pro was the first consumer SSD to arrive on the scene with 3D stacked memory making up its various capacities. The Samsung 850 EVO follows this trend, using another spin of the V-NAND technology for its more affordable range of SSDs. And, affordable it is – even before Black Friday and Cyber Monday deals it’s one of the most price effective SSDs out there.

The new 3D V-NAND - Samsung is calling it vertical NAND - is designed to offer a path up to higher capacity SSDs in the coming years.

The concept of stacked memory is to pile NAND chips on top of each other, with through silicon vias (TSV) providing connections down directly through the stack. This will help boost the bandwidth, as the connections are physically closer, but also means higher capacity drives can be made without relying on the ever-shrinking of NAND modules which make up SSDs.

Samsung's second-gen 3D V-NAND is made up of a full 32 layers stacked atop each other in each module. Those modules have a total density of 86Gbit.


Now, that's not the highest density NAND you'll find in today's drives - both Crucial and Intel are throwing out drives with 128Gbit density NAND in them and have partnered up to create their own 256Gbit 3D NAND for 2015 - but the difference is Samsung is only using 40nm silicon to get there.

Because of the celebrated shrinking of production processes in all spheres of computing - from processors to memory to graphics chips - it might at first seem like this is a backwards step.

We have, after all, become used to using 19nm NAND in our SSDs, even going as low as 16nm, so using a production process that's more than twice as large would surely undo all the performance and efficiency boosts we picked up along the way down.

But because of 3D V-NAND's ability to hit these high densities with such chunky lithography, combined with the bandwidth boosts of the TSVs inside the stacked modules, the larger dies don't have any impact on relative performance.

The efficiency gains from previous production shrinks are also largely offset by the power reductions in the switch from 2D to 3D NAND.

Samsung estimates a 30% reduction in operational power with the Samsung 850 EVO compared with the older Samsung 840 EVO.

Hardy NAND

The 40nm process comes into its own though when we start talking about endurance.

The biggest benefit is the fact the larger production processes are more reliable and longer-lived than their smaller descendants. When you're making the switch, as Samsung is, from the 2-bit multi-layer cell (MLC) design of its higher-end 850 Pro to the less-robust 3-bit MLC, any endurance boost is welcome.

Traditionally 3-bit MLC doesn't last so long as the 2-bit kind, which is why you'll see the Samsung 850 Pro rocking a full ten-year warranty.

With the 40nm 3-bit MLC of the Samsung 850 EVO it does have a shorter five-year warranty, but that's still a good deal longer than the rest of the affordable SSD world with their three-year hedged bets.

But what of performance? Sadly this is where we're in a bit of a holding pattern with solid state drives at the moment. Because of the performance limitations of the SATA 6Gbps interface there's a hard 600MB/s speed limit in place on connected drives.

The solution to this has been the introduction of the M.2 PCIe-based interface, which doesn't have such tight restrictions. Unfortunately they're still limited by the spinning platter HDD legacy of the traditional AHCI protocols which dictate how the interface operates.

This will change once the first non-volatile memory express (NVMe) drives are introduced, combining the PCIe interface with a new standard, designed from the ground up for the NAND memory used in SSDs.

For now though Samsung's consumer drives are all about the ol' SATA 6Gbps interface and so performance really hasn't changed a huge amount from the previous generation of EVO drives.

That is though all relative to the performance hikes we've been spoiled with in the early days of the SSD market.

Spoiled rotten

The Samsung 850 EVO is definitely quicker than the older Samsung 840 EVO, but not by the sort of performance metrics that are going to have you rushing out to upgrade.

The biggest change has been in the write performance of the new Samsung 850 EVO. In sequential terms you're looking at some 20% quicker than the Samsung 840 EVO and a full 30% quicker for the 4k random writes.

The 4k numbers represent the tiny, itty-bitty reads and writes that an operating system will be carrying out on a regular basis as you use your PC. As such they're a good indication of how responsive your PC will be running from that drive.

Samsung 850 EVO open

Those are decent improvements and mean that in the real-world we saw our 30GB Steam folder transfer test resolve twenty-two seconds quicker than the Samsung 840 EVO.

These are the results for the 500GB version of the Samsung 850 EVO, but the introduction of a new Samsung controller - the MGX - for the capacities of 500GB and below has been primarily tuned to provide consistent performance across the range.

That means the performance of the cheaper 250GB version is almost identical.

Still perfectly formed

In fact, the slight difference between the synthetic numbers of the 250GB and 500GB drives could arguably be put down to standard variances in testing.

The real-world scores though are a little slower for the smaller drive. Our zip compression and folder transfer tests show the 500GB drive comfortably ahead.

That might well be down to the TurboWrite tech Samsung uses to speed up its 3-bit MLC drives.

TurboWrite apportions some of the drive's capacity to be used as a form of pseudo single level cell (SLC) NAND. SLC is quicker than the 3-bit MLC used throughout the rest of the drive and acts almost like a speedier form of cache.

There are different amounts of NAND given over to emulating SLC for each capacity of drive; if it follows the Samsung 840 EVO range the 250GB will effectively utilise 3GB of SLC and the 500GB doubles that to 6GB.

If an operation doesn't use the full extent of the pseudo-SLC, and is given time to idle and flush the cache in between tasks, the drive will run at full speed. If it exceeds that limit, such as in our real-world tests, then the drive will revert to a slower 3-bit MLC speed.

This would explain the difference in real-world performance between the different capacity drives, despite their comparable synthetic benchmarks. Our zip test uses a 5GB game folder and the 30GB transfer is a packed Steam installation folder.


Sequential read performance
AS SSD - MB/s: higher is better
Samsung 850 EVO 500GB - 494
Samsung 840 EVO 500GB - 496
Crucial MX100 512GB - 499
SanDisk Extreme Pro 512GB - 506
Samsung 850 Pro 512GB - 528

Sequential write performance
AS SSD - MB/s: higher is better
Samsung 850 EVO 500GB - 485
Samsung 840 EVO 500GB - 409
Crucial MX100 512GB - 474
SanDisk Extreme Pro 512GB - 474
Samsung 850 Pro 512GB - 502

4k random read performance
AS SSD - MB/s: higher is better
Samsung 850 EVO 500GB - 36
Samsung 840 EVO 500GB - 26
Crucial MX100 512GB - 24
SanDisk Extreme Pro 512GB - 30
Samsung 850 Pro 512GB - 37

4k random write performance
AS SSD - MB/s: higher is better
Samsung 850 EVO 500GB - 108
Samsung 840 EVO 500GB - 82
Crucial MX100 512GB - 106
SanDisk Extreme Pro 512GB - 103
Samsung 850 Pro 512GB - 107

Real-world performance
30GB Folder copy - Time in seconds: quicker is better
Samsung 850 EVO 500GB - 208
Samsung 840 EVO 500GB - 230
Crucial MX100 512GB - 191
SanDisk Extreme Pro 512GB - 191
Samsung 850 Pro 512GB - 191

When we're talking about the generational update of an SSD range it's natural to compare it to its predecessor, but arguably the more pertinent comparison is with the competition. The biggest competitor to the Samsung 850 EVO is Crucial's MX100.

Crucial, along with parent-company Micron, is another big name is SSDs and its MX100 range is its price/performance hero right now - especially in the 512GB capacity. It's a tough battle with the 500GB Samsung 850 EVO, with both posting very similar synthetic benchmark numbers.

This new Samsung drive is quicker in terms of sequential writes and 4k reads, but the difference would be practically invisible to the end user. The Crucial drive doesn't use any sort of TurboWrite shenanigans to hit its speeds, however, which explains why its real-world test results are quicker.

The Crucial MX100 512GB is also around $100 (£50) cheaper than this latest Samsung 850 EVO too.

Underneath the 512GB capacity though is where Samsung's new MGX controller really comes into its own.

Crucial's 2D NAND is arranged in 128Gbit 16nm MLC fashion for its MX100 drives, which means the smaller drives need fewer chips to hit their capacities. Which in turn knocks down their performance.

The Marvell controller in the Crucial drive thrives on multi-threaded performance, and if there aren't enough chips to occupy the controller it can't keep up the speeds.

There are no such problems for Samsung though; its 250GB drives perform on almost the same level as its 500GB drives.

If you're looking lower down the capacity stack then it becomes a no-brainer - the Samsung 850 EVO is the go-to affordable SSD.

It's the quickest at that price and comes with a confidence-boosting five year guarantee.

Samsung 850 EVO hero

We liked

The overall performance of the Samsung 850 EVO 500GB is impressive, but not exactly earth-shatteringly different compared with the previous generation of affordable EVO drives.

We are though still talking about a drive that costs around 60c/GB (40p/GB); that's a great price for something which performs this quickly across the board.

We're also impressed with the level of warranty Samsung is offering for its consumer range of drives.

Most SSDs in this category carry three-year warranties where the Samsung 850 EVO gets a full five years. The extra endurance of the 40nm memory should pay dividends in terms of consumer confidence.

The tuning of the MGX controller to maintain performance down through the capacity stack is also very welcome. When you've got other drives, like the Crucial MX100, where performance seriously degrades once you drop below 512GB, that's impressive.

We disliked

As we've said, it's not massively different in terms of performance. It's also not enough quicker than the 512GB Crucial MX100 to really separate it from the cheaper competition at that capacity.

It's also very much a consumer-class SSD rather than one you could reasonably use for storage-heavy productivity tasks, like video editing or intensive photo-manipulation.

The consistent performance of the drive when it's really taking a hammering is relatively low, especially compared to something like the excellent SanDisk Extreme Pro.


The Samsung 850 EVO is another quality, affordable SSD from a company cementing its place as one of the giants of the solid state industry. This 500GB version delivers in the performance stakes, but so do the other, lower-capacity drives too.

The benefits of the 3D V-NAND are evident in the improved endurance of the drive and its longer warranty. Both very welcome things in an industry where consumers are still a little wary of the long-term lifespan of these drives.

Where things get difficult is when you're comparing it to the competition rather than the generation of drives which have come before.

The big tester is the 512GB Crucial MX100. That in itself is a bit of an anomaly - its lower-capacity brethren are far, far slower - but it's still the best price/performance SSD you can buy in the half-terabyte class.

If you're really going to be hammering your drive, but can't pay the exorbitant prices for the pro-level SSDs, then you'd also be better off going for something like OCZ's latest ARC 100 series of drives. They're good-value, quick and incredibly consistent when it comes to heavy usage scenarios.

We're really waiting for Samsung to get its NVMe drives in gear to see serious performance gains in our SSDs then, but in the meantime the Samsung 850 EVO still represents a decent boost over the previous gen EVO drive at all capacities.

The Samsung 850 EVO is the fastest mainstream, consumer-class SSD around, but it's just not quick enough to make anyone reasonably consider it as an upgrade over the previous generation EVO.

from TechRadar - Technology Reviews