Compared to the rapid increases in performance and price reductions in flash storage over the past few years, progress in solid-state drives slowed significantly in 2013 as modern drives plateaued on the SATA III 6Gb / s bus . Current flash products already use the existing SATA specification for sequential reading and writing. Therefore, the industry is expected to switch to SATA Express with PCIe 3.0 for bandwidths of up to 2 GB / s.
This transition will inevitably fuel an entirely new generation of SSDs as companies compete for your hard-earned cash. Until then, however, SSDs will become cheaper and more reliable thanks to improved manufacturing processes.
A recent example would be the OCZ Vertex 450, which offers vector-like speeds at a discount, while today's SanDisk review unit has similar characteristics in terms of providing affordable performance.
We have not reviewed any SanDisk SSDs in the past as they are mostly OEM products. Although they have proven to be reliable, they have barely exceeded the scope. For example, the original SanDisk Extreme SSD was based on the SandForce SF-2281 controller with largely pristine firmware, making it a generic product.
The new Extreme II, on the other hand, has a specially developed firmware that enables it to be set apart from other SSDs with the same controller. It's also noteworthy that the second-generation Extreme series dumped the SandForce controller in favor of the new Marvell 88SS9187, the same controller that the Crucial M500 also uses.
SanDisk is calculating the 240GB Extreme II at a competitive price of around $ 230, just right with the Vertex 450 and also close to the Samsung 840 Pro, which will continue to play a minor role during this review. It should be noted that this drive was a little more expensive (~ $ 250) when it shipped last month. We bet this slight price adjustment will make SanDisk's entry more competitive against the cream of the SSD crop they are certainly aiming for with the Extreme II.
SanDisk Extreme II in detail
The SanDisk Extreme II series is aimed at enthusiasts. The first models offer capacities of 120 GB, 240 GB and 480 GB. The drives have a slim 2.5-inch design with dimensions of 2.75 x 3.96 x 0.28 inches. The power consumption is very low compared to conventional hard drives, as the Extreme II only consumes 0.22 watts when it is active.
The 120 GB model has read and write speeds of 550 MB / s and 340 MB / s. The 240 GB version we have for review is much faster with 550 MB / s reads and 510 MB / s writes, while the 480 GB model has read and write speeds of 545 MB / s and 500 respectively MB / s supported, which is a bit slower than the 240 GB model.
All Extreme ll models are equipped with 19 nm eX2 ABL MLC NAND synchronous flash memory. Our test device contains 16 SanDisk 05226 0646 NAND ICs with 16 GB and a capacity of 256 GB. That said, it is being advertised as a 240GB model because 6% of the original capacity is being used by the nCache.
The nCache is designed to improve data integrity and small write performance. Compared to the original Extreme series, the second generation drives have twice as much nCache available.
After formatting in Windows, the original 240 GB will be converted to 223 GB. However, Windows shows this as 223 GB so it appears that 7% of the original capacity has been lost. With a current retail price of $ 230, the Extreme II 240 GB costs $ 0.95 per gigabyte, a very good value for a high-performance SSD.
The Marvell 88SS9187 controller (code named "Monet") has a dual-core Marvell 88FR102 V5 CPU with shared DTCM and ITCM-SRAM. The controller supports up to 1GB of DDR3-1600 memory buffers, though SanDisk isn't quite as extreme. The 120 GB model receives a 120 MB buffer, the 240 GB model receives a 256 MB buffer, and 512 MB for the 480 GB model. So that's about 1 MB per 1 GB of NAND flash memory.
The SanDisk Extreme II SSD is qualified to provide 80 terabytes of written data with an MTBF of two million hours. Regardless of its MTBF, the Extreme II comes with a very respectable five-year warranty. It's not clear if this rating applies to the 120GB model, and if so, the larger 240GB and 480GB models should last much longer.
It's worth noting that unlike older SSDs like the OCZ Vertex 4, the SanDisk Extreme II doesn't allow AES encryption or eDrive support, which is surprising.