OWC Mercury Accelsior 480GB PCIe SSD Review – First Upgradeable PCIe SSD Hits The Streets

It was only a matter of time before the idea of expandable storage was introduced into the world of PCIe SSDs and, although we have seen a few prototypes in the last year, none have quite made it to market just yet.

Our analysis of the OWC Mercury Accelsior 480GB PCIe SSD not only opens the possibility of upgradeable capacity sizes, but also, it just so happens to be only the second consumer targeted PCIe SSD on the market right now and is both Mac and PC ‘plug and play’ compatible.


The OWC Mercury Accelsior is available in capacities of 120, 240 480 and 960GB.  There are three detachable components which are the PCIe itself and two upgradable ‘blade’ mPCIe SSDs that can be switched off for higher capacity.  Performance of the Accelsior does not suffer the SATA 3 bottleneck at 600MB/s and speeds are listed at 780MB/s read and 648MB/s write.

Similar to only the SuperTalent RAID Drive upStream prototype that we reviewed, the Mercury Accelsior requires no driver installation and is plug and play. Simply insert it into an available PCIe slot in your system and reboot. The Mercury Accelsior has a three year warranty, is available now, and prices are $359.99 (120GB), $529.99 (240GB), $949.99 (480GB) and $2079.99 (960GB). In a search, we found the Accelsior available at OWC and Amazon.Com, for those who want the bigger capacity and can use AmazonPayments.


The OWC  Mercury Accelsior contains a PCIe card and two detachable ”blades’ which are mPCIe SSDs that are typically spoken of as being a ‘gumstick’ design because of their look, although OWC prefers to call them ‘blade’ drives.  The performance of the Accelsior is a result of running both SSDs in a RAID 0 configuration which increases their performance significantly.

The main card houses a Marvell 88SE9230 RAID controller under the heatsink which is significantly small in size and prevents removal of the heatsink for shots.  This host controller connects the two SATA 3 SSDs to the PCIe 2.0 host and will allow up to 1GB/s bandwidth in ideal conditions.  The controller actually supports four devices which becomes an interesting consideration when you look at the back of the card.

Each mPCIe blade SSD contains the SandForce SF-2281 controller and eight pieces of Toshiba 32Gb 24nm Toggle Mode mlc NAND flash memory for a total of 256GB RAW capacity on each SSD.  SandForce firmware and over provisioning needs reduce the capacity of each to 240GB which provides for 480 total advertised capacity.

Final formatted capacity is 447 GB, but remember, this is one of those rare storage devices where you can upgrade the capacity as needed and as it becomes affordable. Here is a pik of the card in one of our Test Bench’s: