Ask a tech enthusiast to name the top solid-state drive (SSD) manufacturers, and they'll likely name companies like OCZ, Corsair, or Samsung. SanDisk is a major player in the memory market, but the company has spent the last few years focusing on providing drives for OEMs like Dell, HP, and Apple.
High-end consumer performance has been less of a priority – or at least it used to be. The SanDisk Extreme II 480GB is meant to kick off a new high-end assault on the consumer market. Based on our tests, it does so quite well – in fact, well enough to grab it a Best Buy award.
The Extreme II uses Marvell's 88SS9187 controller. That's the same chip that powers Plextor's M5 Pro family, but SanDisk has made some changes that enhance the drive's performance, improve reliability, and decrease the chance of data loss in a sudden power outage. All of the new SanDis006B Extreme II SSDs incorporate a small amount of what the company calls nCache built from SLC (single-layer cell) NAND.
As the name implies, SLC NAND stores one bit of information per memory cell compared to two bits for MLC (multi-level cell) and three for TLC (triple-layer cell). It's faster than MLC NAND, takes less energy to program, and holds up better over the long term. The downside to SLC, and the reason that it isn't used more widely in consumer products, is that it's far more expensive.
SanDisk has got around that problem somewhat by deploying small amounts of SLC on every NAND flash chip. These SLC blocks form a second cache layer between the NAND controller and the NAND flash, as shown in the image below. Reading and writing to the SLC NAND is much quicker than writing through to MLC, which reduces the chances of data loss. SanDisk is also able to leverage its own vertical integration in this market; the new drives use SanDisk's own 19nm Flash and a custom firmware solution.
We tested the SanDisk Extreme II 480GB using our trusty Asus P877V-Deluxe motherboard with 8GB of DDR3-1600 and an Intel Core i7-3770K CPU. The P877-V Deluxe offers multiple SATA controllers from Intel and Marvell; all of the drives were connected to Intel's 6G SATA port.
We compared the SanDisk against the Samsung 840 and 840 Pro at 250GB and 256GB, respectively. We'd have preferred to use a suite of high capacity SSDs but modern drives in the necessary form factors weren't available. While higher capacity SSDs are often faster than slower ones, the majority of the delta lies between 60GB to 256GB drives. Once an SSD's memory channels are populated, the difference between a 256GB and 512GB drive is typically quite small.
The performance figures for AS-SSD reflect a drive's performance in a particular type of data workload. Sequential read/write tests measure an SSD's capabilities when reading or writing a large block of contiguous data. A single large movie or ISO image will test a drive's sequential performance (assuming that the target drive isn't badly fragmented). The Extreme II 480GB hit 485MBps sequential read and 460MBps sequential write, compared to 518MBps and 481MBps respectively for the Samsung 840 Pro, and 517MBps/245MBps for the Samsung 840. The Samsung 840 uses slower TLC NAND and takes a performance hit to writes as a result, while the 840 Pro maintains high speed across both reads and writes.
In 4K read/write tests across 64 simultaneous threads, the SanDisk Extreme II hit 355MBps read and 249MBps write speeds. Again, that puts it ahead of the Samsung 840 (330MBps and 187MBps) but behind the Samsung 840 Pro’s 381MBps read and 299MBps write speed.
AS-SSD's also includes a real-world file copy test with three presets – ISO files, program files, and game files. Each type of file is a different size and includes a different amount of compressible data. We reboot in between benchmark runs of this test and throw out the outliers to prevent data caching in Windows or on-drive from polluting the results. In this test, the SanDisk Extreme II hit 309MBps when copying CD image (ISO) files, 206MBps when copying program data, and 228MBps for game files. The Samsung 840 and Samsung 840 Pro were both moderately faster in ISO copying (365MBps for the Samsung 840 Pro, 339MBps for the Samsung 840) but fell behind in program files, where the Samsung 840 Pro hit 179MBps and the Samsung 840 hit 153MBps.
In game copying tests, the two Samsung drives split the difference with the SanDisk Extreme II. The 840 Pro was significantly faster – 292MBps versus the SanDisk's 228MBps – but the 840 standard clocked in at 195MBps.
Finally, there's PCMark 7, which is a different type of test. The benchmark uses real storage workloads created by recording traces of hard drive activity when playing games, loading music or video, or copying files. These traces are used to measure the performance of storage products in comprehensive real-world scenarios. Here, the SanDisk Extreme II's score of 5373 again splits the difference between the 840 Pro's 5588 (still the fastest we've tested) and the Samsung 840's 5,265.
Performance on the SanDisk is good. It's not quite up with the Samsung 840 Pro in certain tests, but it's definitely towards the upper end of the spectrum. How the price compares, however, depends on what you're looking for.
If you want a cheap SSD in the 480GB-512GB range, you can beat the SanDisk Extreme II 480GB's price tag easily. The performance of such a cheaper large SSD, however, is another question altogether. While IOPS (Input/Output Operations per second) are only loosely correlated to real-world performance, the 480GB Agility III SSD from OCZ claims 35,000 IOPS read and 30,000 write. The Extreme II 480GB is rated for 97,000 and 75,000 respectively.
Now, there's nothing wrong with buying a lower-end budget SSD because you value storage space over speed and want a drive that provides more of the former while maintaining many of the benefits of the latter. But we suggest evaluating the Sandisk Extreme II against other SSDs in its weight class.
Compared to SSDs that offer approximately equal performance, such as the aforementioned Samsung 840 Pro which is priced at around the £370 mark, the SanDisk Extreme II represents excellent value for money, and as such it earns our Best Buy award.