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


The SSD Review uses benchmark software called PCMark Vantage x64 HDD Suite to create testing scenarios that might be used in the typical user experience. There are eight tests in all and the tests performed record the speed of data movement in MB/s to which they are then given a numerical score after all of the tests are complete. The simulations are as follows:

  • Windows Defender In Use
  • Streaming Data from storage in games such as Alan Wake which allows for massive worlds and riveting non-stop action
  • Importing digital photos into Windows Photo Gallery
  • Starting the Vista Operating System
  • Home Video editing with Movie Maker which can be very time consuming
  • Media Center which can handle video recording, time shifting and streaming from Windows media center to an extender such as XBox
  • Cataloging a music library
  • Starting applications

If you are new to testing and considering benchmark software, this is the best you can get because the program goes well beyond the results of simulated testing as we have already done. In comparing SATA 2.0 SSDs, we have reached the bandwidth limit and the performance of most new SATA 2 SSDs is as high as it can get with typical high sequential access speeds in the area of 280MB/s read and 270MB/s write.

We needed a way to differentiate these drives and to find a method that can actually put one drive above another and this is exactly what Vantage testing does. Its tests combined can provide an accurate comparison between drives and its tests individually can assist a smart shopper in finding the best SSD for their needs. Next to actual ‘true to life’ testing which can take an insurmountable length of time, PCMark Vantage is the only program that can compare any SSD, side by side, regardless of SATA interface or controller in use.


The PCMark Vantage Total Point Score of the Mercury Accelsior was 40637 with a high transfer speed of 296MB/s which we thought very unusual.  As a result, we conducted the test a total of eight times on three different systems and all results were similar.  This is not indicative of all the other results we have received except for one consistent factor which was the low 4k random write score. If this were the case, that would mean our culprit would be the Marvell RAID controller once again and definitely not the individual blade SSDs which we are sure would have been in the 60,000 point mark.


It has been sometime in the making but the OWC Accelsior speaks to innovation in a big way and is definitely one of a kind.  It is only the second PCIe SSD that is now on the market and available to the consumer and has already hit Amazon, although it can be purchased directly through OWC which I might recommend.  It is definitely the first of it’s kind, in that, one can buy the 120GB and swap OWC ‘blade’ SSDs up to 960GB, as additional capacity is needed.

Of course performance remains constant regardless of size and the blades get a tad more expensive as capacity grows but one can’t fail to see the possibilities in such a device.  Even today, OWC could easily strap on two more mPCIe interfaces on the back of this card and stretch the performance to the 1GB/s limit while, at the same time, making this a PCIe card capable of a high capacity of 1920GB.  This is only possible as the Marvell 88SE9230 RAID controller supports four mPCIe devices, whereas only two are bing used in this configuration.

blankWith respect to performance, it was nice to see the SSD stand up to it’s specifications of 780MB/s read and 648MB/s write performance but what was even better to see were the results of over 530MB/s when testing with incompressible data as one might see in music, movies and photographs.  This enables recommendation to professionals that work in that type of media which cannot always be made with some of todays value minded solid state drives.  Conversely, we definitely would have liked to see the low 4k random write score come in with higher performance as well.

There is something that we really like about this SSD and that is that is only took a second to click into an empty computer PCIe slot, reboot and it was ready to go, simple as that.  There are no drivers needed as well as no need to dig into the bios for configuration concerns. Add to that the fact that it is equally compatible for both PC and Mac computers and things just look that much better.  As for price and availability, we would have liked to see it a bit lower pulling it out of that ‘niche’ market, however, it is available for purchase now which is something few others can say.  Excellent entry OWC!

The Mercury Accelsior PCIe SSD is just too interesting not to present with our Innovation Award!


Check out OWC Accelsior prices at OWC and Amazonblank or, better yet, bookmark our Amazon SSD Store to check daily for the best in SSD prices!

User Rating: Be the first one !


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    Is it bootable?

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    can i use trim comand? does it have a garbage collector? after intensive use of the drive will it perform slower?

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      No TRIM would not work with this RAID 0 configuration, however, Garbage Collection would do its job with the SandForce drives. Unfortunately, the product doesn’t remain with us for a long period so any degradation cannot be measured through continuance use and analysis.

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      no, yes, yes

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    Does the drive maintain the same performance figures in its smaller configuration (120GB)?

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    It seems wrong to call this card a PCIe SSD card as such since it is really a Raid/HBA card which happens to accept mPCIe SSD’s on the board itself. And just why wasn’t this card manufactured with the ability to install 4 mPCIe SSD’s from the get go?

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      The Accelsior uses the Marvell 88SE9230 which only supports PCIe 2.0 x2 which only allows up 1000 MB/s. You would need to use a chip with 4 lanes (such as the Marvell 88SE9445) to get the full performance out of 4 SSD’s. Maybe that chip doesn’t have the boot ability that OWC advertises.

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    Would you happen to know/offer any card or adaptor to connect an SSD like this (https://www.toshiba.com/taec/news/press_releases/2010/memy_10_604.jsp) and retrieve the data? It is the SSD from an Asus UX31 and I think the connection is similar to the ones of the SSDs in the newer versions of the Macbook Air.

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    Please run CrystalDewWorld’s DiskMark with a larger test size. At 1000MB, the filesystem cache can skew results upwards. For example, running DiskMark w/1000MB on my system shows read/write operations around 480MB/s. Cranking up the test size to 4000MB returns a more realistic 290MB/s — appropriate for a SATA II SSD drive.

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    I’m a bit puzzled as to exactly a PCIe SSD card does for a computer. I have an older Intel MAC Pro tower used mostly for audio recording and am trying to extract a bit more performance from the box during in-the-box multi-track audio recording. Does this device essentially only increase the read/write performance between the computer and external drives or are there other benefits? TIA

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    spotted something that needs correction in your review- SandForce SF-2281 is a SATA controller not PCIe, and the Marvell RAID controller is also a SATA part. Not sure where you got the idea that the SSDs in this review were PCIe, but they are not.

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      The review is correct and it is not stated that the SF-2281 is a PCIE controller. This package is a PCIE product, in that, it is connect d via this route. Thanks anyway.

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        Thanks for your quick reply- however your review states
        ‘There are three detachable components which are the PCIe itself and two upgradable ‘blade’ mPCIe SSDs that can be switched off for higher capacity.’
        You have clearly referred to the SSDs as mPCIe which is not correct. Thanks anyway.

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        I am curious what validation you might have to prove this. Considering both the RAID controller and SSD controller are both PCIE compliant, your opinion should be validated in some way. Simply because the connector of the blade SSDs is custom, does not mean the term still cannot be used for best explanation to the reader, similar to the way one compares an Apple SSD to that of the M2.

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        The use of mPCIe was used as the best explanation at the time for the custom connector. While you are correct that the controller is SATA on each blade SSD, this custom solution is a PCIE design. Thanks again.

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