Remember Intel’s old X25-M SSD? The drive came out in 2008 and played a big role in seeding a solid-state storage revolution that continues to sweep across the PC industry. SSDs have come a long way since those early days, when the X25-M 80GB was considered a relative bargain at $600. That worked out to seven dollars per gigabyte, a far cry from the sub-$1 prices that have democratized the technology in recent years.

There is perhaps no better illustration of how far we’ve come than Crucial’s new M500 SSD. For the same $600 asking price as the old X25-M, one variant of the M500 delivers a staggering 960GB of storage. Do the math, and you’re looking at 63 cents per gig—an order of magnitude reduction in cost. How’s that for progress?

Fittingly, these lower prices have been driven in part by cooperation between Intel and Micron, Crucial’s parent company, who collaborate on NAND production through a joint venture dubbed IM Flash Technologies. IMFT fabbed the 50-nm flash chips for the X25-M, and it has since moved to finer process tech at 35, 25, and now 20 nanometers. Each new process packs more gigabytes per wafer, increasing bit densities and decreasing prices.

While the M500 960GB represents a sort of pinnacle for SSD progression, its $600 price tag is still rather steep. The 240 and 480GB versions are more affordable, and those are the ones we’ve gathered to review today. As you’ll see, there’s much more to the M500 than its peak capacity.

Meet the new flash

As you’ve probably deduced already, the M500’s MLC memory chips are built on a 20-nm manufacturing process. There’s a difference between this NAND and what’s lurking inside Intel’s 20-nm 335 Series, though. The memory chips in the Intel and most other contemporary SSDs weigh in at 64Gb (8GB) each, while the M500’s NAND chips have twice that capacity.

This is the first drive we’ve seen with 128Gb NAND, and the shift has interesting implications. For one, it makes hitting higher capacities possible with fewer dies, which is probably part of the reason the 960GB drive costs much less than its terabyte-class peers. Having fewer dies isn’t always better, though. SSD controllers rely on parallelism for maximum performance; past a certain point, drives with fewer NAND dies are actually slower.

With most SSDs, performance starts to fall off at capacities below 240-256GB, suggesting that current controllers favor 32-die configurations. That makes sense, since most controllers have eight channels and can address four chips per channel. The M500 240GB uses only 16 flash dies, and its performance specifications reveal that configuration isn’t ideal.

Capacity Die config Max sequential (MB/s) 4KB random (IOps) Price $/GB Read Write Read Write 120GB 8 x 128Gb 500 130 62,000 35,000 $130 $1.08 240GB 16 x 128Gb 500 250 72,000 60,000 $210 $0.88 480GB 32 x 128Gb 500 400 80,000 80,000 $395 $0.82 960GB 64 x 128Gb 500 400 80,000 80,000 $600 $0.63

To see the M500’s full performance potential, you’ll need at least the 480GB version. The 240GB model has a much slower sequential write speed rating, and its random I/O rates are lower, as well. The 120GB drive is slower still, with only one NAND die for each of the controller’s eight channels. No wonder Crucial is skipping a 60GB variant.

There’s no difference in the performance ratings attached to the 480 and 960GB models, though. Also, note how the per-gigabyte price goes up as the drive capacity drops. Somewhat surprisingly, the 960GB drive delivers the best value of the bunch; it’s the only one that dips close to 60 cents per gig. The prices for the other models are nothing special.

Beneath its grey metal exterior, the M500 is anchored by a Marvell 88SS9187 controller chip. This is an eight-channel design with, you guessed it, four chip-enables per channel. The controller combines a dual-core CPU with a 6Gbps SATA interface and support for DDR3 cache memory. It also has a built-in RAID engine and hardware support for 256-bit AES encryption.

The RAID engine works in conjunction with RAIN, a flash redundancy scheme that’s also employed by Micron’s enterprise-grade SSDs. This mechanism reserves a portion of the flash for parity data, which is why the M500 series has somewhat lower capacities, similar to those of SandForce-based drives.

Crucial also takes advantage of the Marvell controller’s encryption hardware. The M500 supports the TCG Opal 2.0 and IEEE 1667 standards, making it compatible with the BitLocker encryption built into Windows 8. This is the first SSD we’ve seen with explicit support for Win8’s encryption tech.

In addition to protecting bits and bytes from prying eyes, the M500 guards against data loss due to unexpected power failures. See all the little capacitors in the bottom right corner of the circuit board pictured above? Those store enough power to allow the M500 to shut down gracefully if the lights go out or your battery dies.

Speaking of mobile applications, the M500 comes in a slim 7-mm form factor compatible with thinner notebooks. The drive still has the standard mounting holes used by all 2.5″ notebook drives, and Crucial includes an adhesive-backed spacer to ensure a tight fit in 9.5-mm notebook bays. Versions of the M500 with even smaller mSATA and NGFF M.2 form factors are also in the works, although they’ll be limited to 480GB and smaller capacities.

To deal with cramped notebook internals that have little airflow, the M500 employs an adaptive thermal management system. If the drive temperature exceeds 70°C, “NAND operations” are reduced by “approximately 40%” until thermals return to normal. This throttling doesn’t affect the speed of the SATA link, but it will lower overall drive performance.

Like most consumer-grade SSDs, the M500 is covered by a three-year warranty. Crucial says the drive can withstand 40GB of writes per day for five years, which works out to 72 terabytes—plenty for even relatively heavy use. It’s worth noting that this endurance specification is considerably more optimistic than the one slapped on Intel’s 335 Series SSD. That 20-nm drive is only rated for 20GB per day for three years, or 22TB in total.

The effects of cell degradation and interference are more pronounced on NAND chips built with finer fabrication processes, so the M500’s generous endurance rating is certainly comforting. Unfortunately, there doesn’t appear to be any way to monitor flash wear or how many bytes have been written to the drive. Unlike rivals Intel and Samsung, Crucial doesn’t provide utility software with a built-in health indicator. The M500’s payload of SMART attributes doesn’t contain any references to flash wear or bytes written, either. Several of the SMART attributes are labeled “Vendor-specific,” but you’ll need to guess what they track and read the associated values using third-party software.

Without accompanying software, the M500’s overall package feels especially spartan. It doesn’t help that the drive is shipped without the 3.5″ bay adapter commonly included with 2.5″ SSDs. That plastic spacer is the only other thing in the box.

Our testing methods

If you’re familiar with our testing methods and hardware, the rest of this page is filled with nerdy details you already know; feel free to skip ahead to the benchmark results. For the rest of you, we’ve summarized the essential characteristics of all the drives we’ve tested in the table below. Our collection of SSDs includes representatives based on the most popular SSD configurations on the market right now.

Interface Cache Flash controller NAND Corsair Force Series 3 240GB 6Gbps NA SandForce SF-2281 25nm Micron async MLC Corsair Force Series GT 240GB 6GBps NA SandForce SF-2281 25nm Intel sync MLC Corsair Neutron 240GB 6GBps 256MB LAMD LM87800 25nm Micron sync MLC Corsair Neutron GTX 240GB 6GBps 256MB LAMD LM87800 26nm Toshiba Toggle DDR Crucial m4 256GB 6Gbps 256MB Marvell 88SS9174 25nm Micron sync MLC Crucial M500 240GB 6Gbps 256MB Marvell 88SS9187 20nm Micron sync MLC Crucial M500 480GB 6Gbps 512MB Marvell 88SS9187 20nm Micron sync MLC Intel 335 Series 240GB 6Gbps NA SandForce SF-2281 20nm Intel sync MLC Intel 520 Series 240GB 6Gbps NA SandForce SF-2281 25nm Intel sync MLC OCZ Agility 4 256GB 6Gbps 512MB Indilinx Everest 2 25nm Micron async MLC OCZ Vector 256GB 6Gbps 512MB Indilinx Barefoot 3 25nm Intel sync MLC OCZ Vertex 4 256GB 6Gbps 512MB Indilinx Everest 2 25nm Intel sync MLC Samsung 830 Series 256GB 6Gbps 256MB Samsung MCX 27nm Samsung Toggle MLC Samsung 840 Series 250GB 6Gbps 512MB Samsung MDX 21nm Samsung Toggle TLC Samsung 840 Pro 256GB 6Gbps 512MB Samsung MDX 21nm Samsung Toggle MLC WD Caviar Black 1TB 6Gbps 64MB NA NA

To illustrate how this crop of SSDs stacks up against mechanical storage, we’ve thrown a Western Digital Caviar Black 1TB into the mix. Don’t expect this 7,200-RPM hard drive to keep up; it’s included for reference only.

We used the following system configuration for testing:

Processor Intel Core i5-2500K 3.3GHz Motherboard Asus P8P67 Deluxe Bios revision 1850 Platform hub Intel P67 Express Platform drivers INF update 9.2.0.1030 RST 10.6.0.1022 Memory size 8GB (2 DIMMs) Memory type Corsair Vengeance DDR3 SDRAM at 1333MHz Memory timings 9-9-9-24-1T Audio Realtek ALC892 with 2.62 drivers Graphics Asus EAH6670/DIS/1GD5 1GB with Catalyst 11.7 drivers Hard drives Corsair Force 3 Series 240GB with 1.3.2 firmware Corsair Force Series GT 240GB with 1.3.2 firmware Crucial m4 256GB with 010G firmware WD Caviar Black 1TB with 05.01D05 firmware OCZ Agility 4 256GB with 1.5.2 firmware Samsung 830 Series 256GB with CXM03B1Q firmware Intel 520 Series 240GB with 400i firmware OCZ Vertex 4 256GB with 1.5 firmware Corsair Neutron 240GB with M206 firmware Corsair Neutron GTX 240GB with M206 firmware Intel 335 Series 240GB with 335s firmware Samsung 840 Series 250GB with DXT07B0Q firmware OCZ Vector 256GB with 10200000 firmware Samsung 840 Pro Series 256GB with DXM04B0Q firmware Crucial M500 240GB with MU02 firmware Crucial M500 480GB with MU02 firmware Power supply Corsair Professional Series Gold AX650W OS Windows 7 Ultimate x64

Thanks to Asus for providing the systems’ motherboards and graphics cards, Intel for the CPUs, Corsair for the memory and PSUs, Thermaltake for the CPU coolers, and Western Digital for the Caviar Black 1TB system drives.

We used the following versions of our test applications:

Some further notes on our test methods:

To ensure consistent and repeatable results, the SSDs were secure-erased before almost every component of our test suite. Some of our tests then put the SSDs into a used state before the workload begins, which better exposes each drive’s long-term performance characteristics. In other tests, like DriveBench and FileBench, we induce a used state before testing. In all cases, the SSDs were in the same state before each test, ensuring an even playing field. The performance of mechanical hard drives is much more consistent between factory fresh and used states, so we skipped wiping the HDDs before each test—mechanical drives take forever to secure erase.

We run all our tests at least three times and report the median of the results. We’ve found IOMeter performance can fall off with SSDs after the first couple of runs, so we use five runs for solid-state drives and throw out the first two.

Steps have been taken to ensure that Sandy Bridge’s power-saving features don’t taint any of our results. All of the CPU’s low-power states have been disabled, effectively pegging the 2500K at 3.3GHz. Transitioning in and out of different power states can affect the performance of storage benchmarks, especially when dealing with short burst transfers.

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at a 75Hz screen refresh rate. Most of the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

HD Tune — Transfer rates

HD Tune lets us present transfer rates in a couple of different ways. Using the benchmark’s “full test” setting gives us a good look at performance across the entire drive rather than extrapolating based on a handful of sample points. The full test gives us fodder for line graphs, which we’ve split up by drive maker. You can click the buttons below each line graph to see how the M500s compare to different SSDs.





The M500s’ sequential read speeds are consistent across the full extent of the drives, and only Samsung’s 840 Series SSDs maintain higher speeds. There’s no difference between the M500 models here; both trump the old Crucial m4 by 28MB/s.





Things get a little, well, weird when we switch to HD Tune’s sequential write speed test. The m4 actually has a higher average speed this time around, and the M500s are way down in the standings overall. A look at the line graphs provides some insight as to why. The write speeds of the M500 drives are mostly lower than those of the m4, but they spike way up at regular intervals, with the 480GB variant hitting higher peaks than the 240GB.

Now, the M500 isn’t the only SSD to exhibit a repeating pattern of brief write speed increases. All the SandForce-based drives show similar sawtooth profiles. So do the Corsair Neutrons, which are built around a controller from Link_A_Media Devices. This is the first time we’ve seen the behavior from a Marvell-based drive, though.

HD Tune runs on unpartitioned drives, with no file system in place, which might explain the spikes on some of the SSDs. For another take on sequential speed, let’s turn to CrystalDiskMark, which runs on partitioned drives. We used the benchmark’s sequential test with the default 1GB transfer size and randomized data.

The M500s don’t do as well in CrystalDiskMark’s read speed test. They’re a little slower than the Crucial m4 and sit in the middle of the pack. As in HD Tune, the M500 240GB has no problem keeping up with its larger sibling.

That’s not the case in the write speed test, where the 240GB model is 163MB/s slower than its big brother. The smaller M500 languishes toward the back of the pack with budget drives like the Samsung 840 Series, while the 480GB model flirts with the podium. There’s still a sizable gap between the larger M500 drive and the leaders, though.

HD Tune — Random access times

In addition to letting us test transfer rates, HD Tune can measure random access times. We’ve tested with four transfer sizes and presented all the results in a couple of line graphs. We’ve also busted out the 4KB and 1MB transfers sizes into bar graphs that should be easier to read without the presence of the mechanical drive.

The line graph is pretty much unreadable if you’re looking for differences between the SSDs, but it does a rather nice job of highlighting the massive gap in random read access times between solid-state and mechanical storage. Even at the 1MB transfer size, where the SSDs start slowing noticeably, the hard drive is still about an order of magnitude slower.

Among the flash-based contenders, the M500s look pretty good. They’re near the front of the pack in the 4KB and 1MB tests. Admittedly, they’re not alone. Quite a few drives are within spitting distance of the lead, particularly with 1MB random reads.

For the most part, the results of the random write tests are similar. The mechanical drive is outclassed, and the SSDs are on largely even footing. The exception is the 1MB random write test, which shows greater separation between the SSDs—and between the M500s. The 480GB model has much lower access times than its 240GB counterpart, but it’s not quick enough to keep up with the top dogs.

TR FileBench — Real-world copy speeds

Concocted by resident developer Bruno “morphine” Ferreira, FileBench runs through a series of file copy operations using Windows 7’s xcopy command. Using xcopy produces nearly identical copy speeds to dragging and dropping files using the Windows GUI, so our results should be representative of typical real-world performance. We tested using the following five file sets—note the differences in average file sizes and their compressibility. We evaluated the compressibility of each file set by comparing its size before and after being run through 7-Zip’s “ultra” compression scheme.

Number of files Average file size Total size Compressibility Movie 6 701MB 4.1GB 0.5% RAW 101 23.6MB 2.32GB 3.2% MP3 549 6.48MB 3.47GB 0.5% TR 26,767 64.6KB 1.7GB 53% Mozilla 22,696 39.4KB 923MB 91%

The names of most of the file sets are self-explanatory. The Mozilla set is made up of all the files necessary to compile the browser, while the TR set includes years worth of the images, HTML files, and spreadsheets behind my reviews. Those two sets contain much larger numbers of smaller files than the other three. They’re also the most amenable to compression.

To get a sense of how aggressively each SSD reclaims flash pages tagged by the TRIM command, we run FileBench with the solid-state drives in two states. We first test the SSDs in a fresh state after a secure erase. They’re then subjected to a 30-minute IOMeter workload, generating a tortured used state ahead of another batch of copy tests. We haven’t found a substantial difference in the performance of mechanical drives between these two states. Let’s start with the fresh-state results.

Again, we see the M500 240GB lagging behind the 480GB drive. The gaps are widest with the larger files in the movie, RAW, and MP3 sets. All the drives slow down with the smaller files in the Mozilla and TR sets, and the differences between them shrink, as well.

The M500 480GB offers decent performance overall. It bounces between fourth and fifth place with larger files and isn’t too far out of the lead with smaller ones. The 240GB model sits much lower in the standings and even loses a round to the previous-generation Crucial m4. That older drive slows way down with smaller files, so even the M500 240GB offers a big improvement in the TR and Mozilla test patterns.

Our used-state results reveal that the M500s don’t slow down appreciably after being hammered by our IOMeter torture test. The 240GB version is actually little bit faster when copying our RAW and MP3 files in this used state, but the differences amount to just 8% and 5%, respectively.

TR DriveBench 1.0 — Disk-intensive multitasking

TR DriveBench allows us to record the individual IO requests associated with a Windows session and then play those results back as fast as possible on different drives. We’ve used this app to create a set of multitasking workloads that combine common desktop tasks with disk-intensive background operations like compiling code, copying files, downloading via BitTorrent, transcoding video, and scanning for viruses. The individual workloads are explained in more detail here.

Below, you’ll find an overall average followed by scores for each of our individual workloads. The overall score is an average of the mean performance score for each multitasking workload.

DriveBench shows almost no preference between the M500 SSDs. The 240GB model scores only slightly lower than the 480GB one, sandwiching Samsung’s 840 Pro near the middle of the pack. The top drives have a comfortable lead over Crucial’s new hotness, but perhaps the M500s stole the spotlight in one of the individual tests. Let’s look.

Nope. Even their positions relative to the other SSDs are largely consistent across our multitasking workloads.

In some cases, the two M500 models have identical performance. They’re close to even with the Crucial m4 in a few of the workloads, too, but the new drives are clearly faster when our multitasking load involves code compiling and file copying.

TR DriveBench 2.0 — More disk-intensive multitasking

As much as we like DriveBench 1.0’s individual workloads, the traces cover only slices of disk activity. Because we fire the recorded I/Os at the disks as fast as possible, solid-state drives also have no downtime during which to engage background garbage collection or other optimization algorithms. DriveBench 2.0 addresses both of those issues with a much larger trace that spans two weeks of typical desktop activity peppered with multitasking loads similar to those in DriveBench 1.0. We’ve also adjusted our testing methods to give solid-state drives enough idle time to tidy up after themselves. More details on DriveBench 2.0 are available on this page of our last major SSD round-up.

Instead of looking at a raw IOps rate, we’re going to switch gears and explore service times—the amount of time it takes drives to complete an I/O request. We’ll start with an overall mean service time before slicing and dicing the results.

Our two-week trace teases out a substantial difference between the M500s. The 480GB model’s mean service time is half that of the 240GB drive, which is the slowest of the SSDs. Even the old Crucial m4 is more responsive overall. The larger of the M500 drives manages to claw its way to the middle of the pack, just ahead of the Samsung 840 Series.

We can learn a little more about what’s going on in DriveBench by splitting the mean service time between read and write requests.

Well, there’s your problem right there. The M500s have comparable read service times, but writes are another story. The mean write service time of the 240GB model is three times higher than that of the 480GB one. Even the mechanical drive looks better according to that metric.

If you consider just the M500 480GB, it looks like Crucial has made nice improvements in write responsiveness versus the old m4. Too bad those improvements also come with higher density NAND dies that compromise the performance of lower-capacity models.

There are millions of I/O requests in this trace, so we can’t easily graph service times to look at the variance. However, our analysis tools do report the standard deviation, which can give us a sense of how much service times vary from the mean.

The M500 240GB’s higher write service times come with a side order of increased variance. Neither of the M500 drives does well in our write variance metric, though. The m4 also struggles, suggesting that Crucial DNA is responsible. At least the drives’ read service times are more consistent.

We can’t easily graph all the service times recorded by DriveBench 2.0, but we can sort them. The graphs below plot the percentage of service times that fall below various thresholds. You can click the buttons below the graphs to see how the M500s compare to the other drives.









The distribution of write service times is actually pretty similar from one SSD to the next. The mechanical drive has much lower percentages of service times under each threshold, of course, but there are only minor differences within the solid-state crowd.

The read distributions are a little more varied, again with the mechanical drive lagging far behind. Here, the Samsung 840 Series SSDs have a clear edge over the M500s. The other contests are much closer, and the two M500 models are closely matched.

As the distribution plots illustrate, the service times over 100 milliseconds make up tiny fractions of the overall results. Those extremely long service times have the potential to cause the sort of hitching that users might notice, so we’ve graphed the individual percentages for each drive.

The M500s suffer from more lengthy read service times than most of the other SSDs, and the 240GB model is the worst of the two. The situation is more dire with writes, where the 240GB M500 has over four times the number of extremely long service times of its 480GB kin. Once again, the M500 only represents an improvement over the old Crucial m4 if you opt for the 480GB version of the new drive.

IOMeter

Our IOMeter workloads feature a ramping number of concurrent I/O requests. Most desktop systems will only have a few requests in flight at any given time (87% of DriveBench 2.0 requests have a queue depth of four or less). We’ve extended our scaling up to 32 concurrent requests to reach the depth of the Native Command Queuing pipeline associated with the Serial ATA specification. Ramping up the number of requests also gives us a sense of how the drives might perform in more demanding enterprise environments.

We run our IOMeter tests using the fully randomized data pattern, which presents a particular challenge for SandForce’s write compression scheme. We’d rather measure SSD performance in this worst-case scenario than using easily compressible data.

There’s too much data to show clearly on a single graph for each access pattern, so we’ve once again split the results by drive maker. You can compare the performance of the M500s to that of the competition by clicking the buttons below each graph.





Surprisingly, the M500s turn in slightly lower transaction rates than their predecessor in the web server test, which is made up exclusively of read operations. The 480GB model has a bit of an edge over the 240GB, but all three Crucial drives are pretty close.

As the scale of these plots suggests, there are better solutions. The Corsair Neutrons, OCZ Vector, and Samsung SSDs all deliver greater I/O throughput in this test, especially as the load ramps up. The M500s are more competitive with SandForce-based drives like the Intel 335 Series, which isn’t bad company to keep.

Don’t waste your time with the mechanical results here. The Caviar Black’s transaction rates are low enough that the line barely hovers above the X axis.













You didn’t think the Crucial m4 was going to maintain its lead over the M500s, did you? Our remaining IOMeter test patterns incorporate a mix of read and write requests, and the M500s are clearly superior to their predecessor with those mixed workloads. The relatively small gap between the M500 models remains, though.

While the Corsair Neutrons still outgun the M500s across the board, the new Crucial drives are more competitive overall. The Vector and Vertex 4 only offer higher transaction rates under heavier loads, and the same goes for the Samsung SSDs.

Boot duration

Before timing a couple of real-world applications, we first have to load the OS. We can measure how long that takes by checking the Windows 7 boot duration using the operating system’s performance-monitoring tools. This is actually the first test in which we’re booting Windows off each drive; up until this point, our testing has been hosted by an OS housed on a separate system drive.

Level load times

Modern games lack built-in timing tests to measure level loads, so we busted out a stopwatch with a couple of reasonably recent titles.

I could write a few sentences about the M500s being a little faster or slower than this or that SSD, but look at the overall times. Most of the solid-state drives are clumped within about a second of each other in all our load tests. You probably won’t notice any difference between them.

You will, however, notice that mechanical storage is much slower. The Caviar Black takes about twice as long as the SSDs to load Windows and Duke Nukem Forever. It’s also about seven seconds behind in Portal 2.

Power consumption

We tested power consumption under load with IOMeter’s workstation access pattern chewing through 32 concurrent I/O requests. Idle power consumption was probed one minute after processing Windows 7’s idle tasks on an empty desktop.

The power consumption of the M500s is surprisingly high given our results for the old m4. That said, most of the SSDs have idle power consumption similar to the newer Crucial drives. Apart from the m4, the M500s consume less power than anything else under load. There’s very little difference in power draw between the 240 and 480GB models.

The value perspective

Welcome to another one of our famous value analysis, which adds capacity and pricing to the performance data we’ve explored over the preceding pages. With the exception of the Samsung 830 Series, which is out of stock at most vendors, we used Newegg prices for all the SSDs. We didn’t take mail-in rebates into account when performing our calculations.

First, we’ll look at the all-important cost per gigabyte, which we’ve obtained using the amount of storage capacity accessible to users in Windows.

If the 240 and 480GB M500s matched the per-gigabyte price of their 960GB sibling, they’d be second only to the mechanical drive in the standings. The Samsung 840 Series occupies that spot instead, and at 68 cents per gig, it’s notably cheaper than either of the M500 models.

Our remaining value calculation uses a single performance score that we’ve derived by comparing how each drive stacks up against a common baseline provided by the Momentus 5400.4, a 2.5″ notebook drive with a painfully slow 5,400-RPM spindle speed. This index uses a subset of our performance data described on this page of our last SSD round-up.

A few things hurt the M500s in our overall index, including their slow HD Tune write speeds and relatively high percentages of extremely long service times in DriveBench 2.0. The 480GB model falls just behind the Samsung 840 Series, and the 240GB version scores lower than the old m4. The M500 240GB really behaves more like a 120GB drive, so we’re not surprised to see it so far down in the standings.

Now for the real magic. We can plot this overall score on one axis and each drive’s cost per gigabyte on the other to create a scatter plot of performance per dollar per gigabyte. The best place on the plot is the upper-left corner, which combines high performance with a low price. We’ve deleted the Samsung 830 Series from the following plot to give the labels a little more room to breathe—and to focus on the drives you can actually buy. The 830 Series has been discontinued, and the few vendors who still have stock are selling it at inflated prices.

The M500 240GB occupies a dismal spot on the plot. It’s slower overall than all the other SSDs, many of which cost less per gigabyte. This plot would surely look different if the 240GB drive were matched up against versions of the other SSDs with similar die counts.

The larger M500 has a more enviable position on the plot, yet there are certainly better values to be had. The Samsung 840 Series, Intel 335 Series, and Corsair Neutron all deliver higher performance at lower per-gigabyte prices, and the 840 Pro is a lot faster for not too much more.