Crucial M500 vs. Samsung SSD 840 EVO - Battle of the Mainstream SSDs
Two Schools of Thoughts
Just weeks ago, we reviewed the top drives from last year in our Great High-end SSD Shootout (2014 Edition). Although the Crucial M500 did not fare too well, we must remember that despite being Crucial’s flagship SSD, it is actually positioned as a mainstream SSD and was not intended to go head to head with the likes of Samsung’s fearsome SSD 840 Pro and OCZ’s blazing quick Vector 150. So this time, we are pitting it against something more apt.
Enter Samsung’s new SSD 840 EVO, successor to the older SSD 840. Like its predecessor, the SSD 840 EVO continues to employ the use of Triple-Level-Cell (TLC) NAND, and remains to be the only major SSD manufacturer to do so in the consumer SSD space. Samsung has also shifted to a smaller 19nm manufacturing process - previously it was 21nm. Finally, the SSD 840 EVO also gets an updated controller. Dubbed the MEX, the underlying architecture of the controller is identical to the old MDX found on the SSD 840 Pro, but benefits from faster running cores that operate at 400MHz as opposed to 300MHz in the MDX.
The SSD 840 EVO also employs two new Samsung technologies to boost its performance: TurboWrite and RAPID. TurboWrite dedicates a small portion of its TLC NAND to work as an SLC write buffer, which is unlike SanDisk’s nCache technology. RAPID, on the other hand, is a caching technology that was introduced in the middle of last year to boost random I/O performance with smaller size data at low queue depths. Essentially, it makes use of unallocated system memory and spare CPU cycles to cache data and boost performance.
The use of TLC NAND is interesting and Samsung believes that this is the most viable solution for bringing the cost of drives down in the future. As its name suggest, TLC NAND stores three bits per cell (eight voltage states) as compared to MLC’s two bits per cell (four voltage states) and SLC’s single bit per cell (two voltage states). What this means is that with TLC NAND, more dies can be harvested from a single wafer and this reduces manufacturing costs.
However, you cannot have your cake and eat it, and there are some downsides to TLC NAND and the two most pressing are performance and endurance. With eight voltage states to check, random reads will take more time - roughly twice as long as MLC NAND (theoretically speaking). Endurance is affected because having additional voltage stages reduces the margin between the individual stages, and this is crucial because as you write to the cell, the layer of silicon oxide that acts as an insulator gradually wears out. When it does, higher voltages will be needed to program the cell to one of its eight states, which further reduces the margin between them. Gradually, the margin will be so small that the cell can no longer be effectively used and has to be retired. Anandtech has a more detailed explanation that you can read up here. Therefore, while MLC NAND SSDs are typically good for 3000 P/E (program-erase) cycles, expect TLC NAND SSDs to enjoy less perhaps as little as 1000.
This is where the Crucial M500 comes in. As the consumer arm of Micron, one of the world’s largest manufacturer of NAND memory, they believe that smaller manufacturing processes coupled with larger page and block sizes is the way forwards. As a result, Micron’s latest NAND die packs a maximum capacity of 128Gbits or 16GB per die. While that might be the same as Samsung’s solution, Micron’s NAND has a larger 16KB page size which may negatively affect latency. On the other hand, since it is still MLC NAND, endurance has not been adversely affected and the M500 is rated for up to 3000 P/E cycles, the same as other MLC NAND SSDs.
As you can see, while the two drives are targeted squarely at mainstream users, the ideology and strategy behind the two are markedly different.
Test Setup
The drives will be tested on our recently revamped storage testbed. The main changes are the faster Core i5-2500K processor and an accompanying Z77 motherboard which has native Thunderbolt connectivity.
Intel Core i5-2500K (3.3GHz)
ASUS P8Z77 Pro Thunderbolt (Intel Z77 chipset)
2 x 2GB DDR3-1600 memory
MSI GeForce 8600 GTS
Windows 7
We have also revised our benchmarks, ditching older benchmarks such as HD Tune and also including an all new timing test to better evaluate the drive’s real world performance.
The list of benchmarks used are as follows:
AS-SSD benchmark 1.7.4739
CrystalDiskMark 3.0.1
PCMark 7 (Storage suite)
Iometer (version 2006.07.27)
Timing Tests (Cold start, Reboot, Apps Launching)
Apart from the Crucial M500 and Samsung SSD 840 EVO, we have also included results of some of the quickest drives in the market today to give an idea of where the two mainstream drives stand in the greater hierarchy of things. We are also interested to see how the new SSD 840 EVO performs against the flagship SSD 840 Pro. Will the newer and faster MEX controller be able to make up for the use of slower TLC NAND?
Crucial M500
Samsung SSD 840 EVO
Samsung SSD 840 Pro
Plextor M5 Pro Extreme
OCZ Vector 150
SanDisk Extreme II
Timing Tests
Looking at our timing tests, we can say that compared to the Samsung SSD 840 EVO, the Crucial M500 was faster on a whole. From a cold start, the Crucial M500 managed to boot up a whopping 2.6 seconds faster - which is considerable for SSDs. It was also faster at rebooting the system, managing 27.8 seconds compared to the SSD 840 EVO’s 28.4 seconds. However, when it came to launching apps, the SSD 840 EVO was three-tenths of a second faster.
In addition, if we were to compare the timings of these two drives against the top tiers drives - such as the Samsung SSD 840 Pro, OCZ Vector 150 and Plextor M5 Pro Xtreme - we can see an appreciable gulf in performance. In practical terms, a couple of seconds may not be much, but it shows that you do pay for what you get and that the premiums that these top tier drives command is not without good reason.
CrystalDiskMark 3.0.1 Results
CrystalDiskMark is an easy-to-run and quick utility to use to gauge a drive’s performance. It measures sequential read and write performance and random read and write speeds of random 4KB, 4KB (queue depth 32) and 512KB data.
The Samsung SSD 840 EVO began brightly, racking up very fast sequential, 512K and 4K read and write speeds that could easily match the top tier drives. Sequential and 512K write speeds were especially impressive when compared to the Crucial M500. However, we noticed that write performance took a significant dip when it came to the intensive 4K, 32 queue depth workload, which suggests that at this point, the TurboWrite cache is insufficient to boost its performance to rival the top tier SSD drives.
AS SSD 1.7.4739 Results
AS SSD is a benchmark that uses non-compressible and completely random data. What this means is that the drives using controllers such as the SandForce SF-2281 cannot compress the data first, which takes away one of their strong advantages and help us score it more evenly against other drives.
The Samsung SSD 840 EVO began impressively on AS SSD, racking up very impressive copy speeds on the Copy benchmark that left the Crucial M500 in the dust and even outclasses the SSD 840 Pro slightly. Sequential and 4K read and write speeds were excellent too and could easily go head to head with the SSD 840 Pro. However, on the intensive 4K, 64 threads workload, we saw performance of the Samsung SSD 840 EVO dip drastically, again suggesting that the TurboWrite cache has been exhausted. Write speeds in particular took a heavy hit.
PCMark 7 Results
PCMark 7 is a benchmarking suite from FutureMark that evaluates the performance of Windows 7 machines. It tests a wide range workloads and aspects of the system ranging from computation, image and video manipulation and storage. We’ll be looking solely at the storage test here.
The Samsung SSD 840 EVO narrowly edged out the Crucial M500 on PCMark 7, scoring about 4% more. The SSD 840 EVO’s scores were also comparable to the Plextor M5 Pro Xtreme and OCZ Vector 150. Looking at the score breakdown, we can see that the Samsung SSD 840 EVO edges the Cruclal M500 in the Importing Pictures, Starting Applications and Gaming workloads.
Iometer Results (Part 1)
Lastly, we put the drives through the rigorous grind of Iometer, with different workloads and I/O queue depths. We have chosen to show results from a queue depth of 1 to 5 as this better represents the workloads a typical consumer might face.
Despite the Samsung SSD 840 EVO’s glowing performances in earlier benchmarks, Iometer proved to be too demanding for the drive as we see it posting somewhat erratic results. Modern SSDs have impressive read speeds and there was little to separate the Crucial M500 and Samsung SSD 840 EVO, and indeed the rest of the drives, on the 64K streaming reads workload. Write performance of mainstream drives tend to be poorer and this was confirmed when we look at the graph of the 64K streaming writes workloads where both the M500 and SSD 840 EVO managed to lowest IOPS.
The SSD 840 EVO’s performance on the File Server workload was particularly poor, but it picked itself up on the Web Server workload. On the flip side, while the M500 managed to put in a decent shift on the File Server workload, subsequently, it managed the lowest IOPS on the Web Server workload.
Iometer Results (Part 2)
Finally, we look at the I/O response times for the workloads reported on the previous page. In the introduction of this shootout, we mentioned that TLC NAND would suffer from latency issues, but as the benchmarks have shown, the Samsung SSD 840 EVO manages to overcome this well, though there instances where its performance was found slightly wanting. Also, we can see that when it comes to write workloads, their poor performance can be attributed to their very high response times.
Mainstream Warriors
As we mentioned in the introduction of this review, the two drives in question here go into battle with two different philosophies. While Samsung believe that cramming more bits per cell is the way forwards; Crucial, on the other hand, is adamant that reducing the size of the NAND die by improving manufacturing processes is the way to go.
From a performance standpoint, the Samsung SSD 840 EVO is very impressive and easily outclasses the Crucial M500 in most benchmarks. What is really amazing is that despite the use of TLC NAND, its performance was mostly a match for that of high-end MLC NAND drives like the Samsung SSD 840 Pro, OCZ Vector 150 and Plextor M5 Pro Xtreme. For that we have to thank its TurboWrite technology, which proved to be effective in most workloads and instances, and only lost its edge on high queue depth workloads.
The Crucial M500 might be the slower drive overall - mostly due to its poor write speeds - but its read performance was still respectable and comparable to the current crop of high-end SSDs. In our timing tests, it was also marginally quicker than the Samsung SSD 840 EVO. This means that the Crucial M500 should fit the bill for most mainstream users nicely, since the desire for an SSD is mostly due to faster boot ups and launching of applications.
For those concerned about endurance and reliability, both brands have had a good track record of reliability and both come with 3-year warranties. As for endurance, TLC NAND will inevitably be at a disadvantage, but this should not be an issue for most mainstream users. A user reported writing over 430TB to a 120GB version of the older Samsung SSD 840 before it finally died. Considering most users would write only 10GB to 30GB to the drive each day, Anandtech has calculated an average lifespan of around 8 years for the 120GB version of the Samsung SSD 840 EVO. Bear in mind also that lifespan increases linearly as you go up the capacity points.
When it comes to pricing, the Crucial M500 has a slight edge on the Samsung SSD 840 EVO. For drives in the 256GB category, depending on where you shop, the Crucial M500 can go for as low as S$215. On the other hand, the Samsung SSD 840 EVO commands a higher asking price of at least S$255 - a difference of S$40 or 18%, which is considerable (and the price differential can get wider depending on where you shop). That said, considering the performance gains that the Samsung SSD 840 EVO offers, the premium is justified. Nevertheless, whether or not these performance gains would be beneficial still depends very much on your own usage. Hence if you are on a very tight budget, we would recommend going with the Crucial M500.
What is interesting to consider is that if we were to look at the smaller 128GB versions of the two drives, we will find that the difference in price is much smaller. In this case, the Samsung SSD 840 EVO is the better catch.
All in all, both drives have their own merits: the Crucial M500 is our pick if you are on a tight budget or if you do lots of write operations and endurance is a top concern, whereas the Samsung SSD 840 EVO offers the best performance for buck at this price bracket.
Before we end, eagle-eyed readers might notice that we did not include results of the Samsung SSD 840 EVO in RAPID mode. Well, stay tuned because we will be investigating this new caching technology deeper in an upcoming article.
