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Closer Look at SanDisk Extreme SSD 240 GB

SanDisk doesn’t offer a wide range of SSDs. Manufacturing various flash-based devices (memory cards in the first place), the company has been rather neglecting the SSD market. For example, it only introduced its own SATA 6 Gbit/s SSDs in the first quarter of this year when the market had already been overpopulated by competitor offers.

The Extreme SSD is a new product, too. As its name suggests, it is also a flagship product. However, the SanDisk Extreme is actually priced like a midrange SSD, sharing the same market category with typical SandForce-based disks equipped with synchronous flash memory from Intel or Micron. So, the pricing looks highly attractive, but what’s the catch?

First of all, the packaging and accessories are far from gorgeous. The SanDisk Extreme 240 GB comes in a small plain-looking cardboard box with no useful information on its sides.


As for the contents of the box, the SSD is shipped without any handy accessories such as an adapter for installing it into a 3.5-inch bay.

The SSD itself looks like a high-quality product, though. It has a robust metallic case painted matte black. Of course, the exterior design of an SSD hardly matters for anyone, yet the Extreme does look top-class compared, for example, with OCZ products.


There are two labels on the case, one with manufacturer and series logos and another with technical information (part number (SDSSDX-240G), capacity, interface type, barcodes, etc). The case is 9.5 millimeters thick.

The SanDisk Extreme seems to utilize a reference PCB from the controller developer but we can’t be sure as we haven’t yet met any other SandForce-based product with 24nm Toggle Mode NAND flash. The PCB of this 240 GB disk is populated by an SF-2281 controller together with eight memory chips. There are eight empty places for more memory which is installed for the 480 GB model.


It is these memory chips that constitute the second special feature of the SanDisk Extreme. Each of them is 32 GB in capacity, containing four 64-gigabit NAND dies. Bearing SanDisk markings, the chips are actually manufactured at Fab 5 which is owned by Flash Forward Ltd, a joint venture of SanDisk and Toshiba. The pedigree is unimportant, though. The main thing is that these chips belong to the new generation: Toggle Mode HBL (hierarchical bit-line) NAND flash memory manufactured on 24 nm tech process out of 300mm wafers. It is the progressive manufacturing technology that allows this memory to compete in pricing with ordinary ONFI 2.0 flash. And that’s why the SanDisk Extreme is comparable in price with the numerous SandForce-based products that have Intel and Micron memory.

24 nm Toggle NAND flash works at a higher clock rate than synchronous ONFI 2.0 flash. However, SSDs with 24 nm Toggle NAND flash are going to be somewhat slower than their predecessors that used the 32 nm version of that memory because the introduction of the new tech process doubled the density of NAND devices and reduced the controller’s interleave level. For example, the SandForce controller uses 8-way interleave in 240 GB SSDs with 32 nm Toggle NAND flash (such as OCZ Vertex 3 MAX IOPS or Mushkin Chronos Deluxe) whereas the SanDisk Extreme 240 GB only supports 4-way interleave.

Here are the official SanDisk Extreme 240 GB specs:

  • Controller: SandForce SF-2281;
  • Interface: SATA 6 Gbps;
  • Flash-memory: synchronous 24 nm Toggle Mode NAND;
  • Size: 240 GB;
  • Cache-memory: none;
  • Sequential read speed: 550 MB/s;
  • Sequential write speed: 520 MB/s;
  • Random read speed ( 4 KB blocks): 39000 IOPS;
  • Random write speed ( 4 KB blocks): 83000 IOPS.

The specifications are typical of SandForce-based solutions with synchronous flash. The capacity is standard as well. As in other SSDs based on the SandForce platform, 14% of capacity is reserved for the RAISE technology (Redundant Array of Independent Silicon Elements), so the user-accessible capacity is 240 gigabytes (or 223 gibibytes out of the full 256 gibibytes).

SanDisk offers the SSD Toolkit utility for its SSDs. It can report the exact model name of the SSD, show its SMART parameters and update its firmware.

The current firmware is version R201 but the version number is the only original thing about it. It is actually based on reference firmware 5.01.

Like most SSDs with SF-2281 controller, the SanDisk Extreme is shipped with a 3-year warranty.

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