OWC Mercury Accelsior E2 PCIe SSD Review – Dual eSATA Performance of 780MB/s Tested and Approved

About a year ago, we published our review of the OWC Mercury Accelsior PCIe card, a storage device that utilize two blade style SSDs in RAID to achieve incredible performance and capacity for your desktop Mac or PC.  The beauty of the Accelsior was that storage was upgradeable, making it a very affordable option for the media professionals growing storage needs. The Accelsior was deserving of our Innovation Award at the time and achieved great performance of 765MB/s read and 740MB/s write.


It wasn’t long after that we were contacted by OWC once again and subsequently reviewed their new Mercury Helios Thunderbolt Chassis that enable external storage of the Accelsior, along with many other solid state drive models.  We tested the Accelsior in the Helios for transfer speeds of 706MB/s read and 593MB/s write performance, but just for kicks, we also through in an Intel 910 Data Center PCIe SSD, valued at somewhere around $3000, that provided results of 900MB/s read and 836MB/s write performance.  Our new found love for Thunderbolt was obvious and that Helios has been front and center on my desk since. Once again, the Helios grabbed our Innovation Award.

OWC Mercury Helios Thunderbolt Chassis

It seems that OWC has been at it once again and we recently received a new OWC Accelsior E2 PCIe SSD, fitted with two 240GB blade SSDs for excellent performance and capacity once again.  The Accelsior is the latest design of the OWC engineering team and contains two 6Gbps eSATA ports that provide for external storage up to 32TB as well as performance similar to the original Accelsior.  Once again, OWC has caught us off guard and this seems to be a first and great idea for increasing performance to another level and increasing capacity significantly.  The beauty of the Accelsior has always been its expansion capabilities but this knocks the original capacity maximum out of the ball park.

eSATA Accelsior 1

We had to marvel in the thought that, utilizing our Helios Chassis, our local storage needs became pretty much limitless and the performance of both the original RAID configuration of the blade SSDs, along with the potential of the two eSATA ports being RAIDED was excellent.  On top of that, details aren’t too clear yet with respect to exact price but OWC is offering an upgrade program for original Accelsior owners.  Let’s take a closer look at the E2.

Accelsior Front

As we can see, the Accelsior remains to be OWC blade SSD driven and the only real difference appears to be the inclusion of the two eSATA ports.  The 0GB card alone (without SSDs) lists for $199, the 240GB version for $479, 480GB for $749, and for those space lovers we have the 960GB for $1329.  Expansion is extensive with SSD upgrading and even adding on a Helios for external storage.


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    Do the eSATA ports support cabinets with port multipliers?

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    Have you tested this beyond the initial testing? I’ve had 3 of these drives fail me in 2 years. Wondering if others have had similar experience or if mine is a fluke. They want to send me another replacement (they have to because it’s under warranty anyways), and I’ll get it, but I’m leary of even installing it after 3 failures

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      Typical review agreements with a few companies is simply that the equipment be returned after the review; this is the case with OWC. WE had not done any extensive testing.

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        That’s too bad. I agree with all of your review, but it’s too bad the drive fails after a year. Have you reviewed any comparable PCIE SSD’s for mac?

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        I find this to be one of the core problems with many reviews or the window and time frame for reviews and I do wish long term testing were more the norm. Regardless I do have to thank you for your comment though because based on what you and Wayne have said I need to do way more research to see if I can understand the problem. Is it the SSD’s that are bad or the cards have some flaw in the design that produces increased stress in a machine with an older architecture and this causes the card to fail? Are they flukes? 3 times?

        That’s very worrisome. Did you end up taking a refund or went with a 4th and how did that work out?

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    i’m a very long-term owc/macsales customer. i bought the 480gb e2 last year and it “failed” about 6 months later.

    what happened was: i came back to the machine after it was in sleep mode (yes, i’d installed the accelsior software) and it was mostly unresponsive. SBBOD for minutes after each mouse click. would accept switching applications. would get maybe one click or move with each before going unresponsive. so i rebooted the machine.

    after reboot, machine was functional but still sluggish. so as a precautionary measure. i quickly backed up the critical client files that were still on it. after another reboot (with another internal) the drive filed to mount. system info saw the device, but nothing showed it as a storage volume. still worked as an esata device. but not a drive

    after a number of support chats and efforts to see it via terminal. we decided that it was most likely “bad blades”. unwilling to accept defeat (and in hopes of retrieving my personal data), i left the card in the machine for a few weeks. as twice it had come up briefly then disappeared again.

    i’d told support that it had also had periodic failures in esata connectivity during this time.

    fast forward a few weeks. i admit defeat and send it in. within 2 weeks they returned it to me at no cost with new blades BUT on my same base PCI card. ok. fine. whatever.

    a few days later it started to do EXACTLY the same thing it had before. BUT this time i had a copy of disk warrior on hand and was able to remedy the problem.

    (if you own an accelsior, i HIGHLY suggest factoring the cost of disk warrior into the purchase).

    i contacted support and asked that given the esata issues, why they would not have sent me an entire new device? they said that it had been extensively tested and had been proven functional. one tech said that it was odd that they would have done that. and i should have been contacted before they made the decision.

    so anyway. i told them that i had every reason to be suspicious of the base card itself. they agreed to send me a new card. but only while putting a hold on my card for the price until the defective one was received in return. i told them that i was unwilling to come out of pocket (even temporarily) for something that shouldn’t have happened in the first place. but they refused to budge.

    i then said “ok. how about since i have no faith in the product. i just return the whole thing for a full refund?” which they approved.

    so basically. they are going to return me $500 for a year old product. rather than simply bypass a charge and refund of $150? go figure.

    i know i’m being super petty at this point. but exemplary customer service and product support was one of the many reasons i stayed both a customer and very vocal supporter for so many years. it seems that like in so many other cases, as a company grows larger, the quality of service takes a downturn : (

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    Philippe Schaedler

    I bought the 960GB December 2015 from OWC – installed it right away today March 17th it failed the second time – first I was able to repair the disk with disk utility – but was much slower than original install – today white screen – I have to erase the disk and migrate – VERY disappointed OWC – Called them they said it had to do with making a carbon copy of the old drive – and seeing in this forum that this is a common occurrence, I will ask for my 658.- back –

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    I was just yesterday reading that the major downfall of the SSD Raid 0, Dual Drive Setup up is that they’re prone to Failure. This was not an OWC Customer or Product, but the Manufacturer of a PCIe Solo and Dual Cards. The same statement did not appear along with the Ad for the Solo Tray, which makes me think that there may be a Bug of some type still undetected. Not a “Bug” – Bug, but a Glitch causing the failure. It may be that even using identical Drives from the Same Mfg. may still have enough variations to cause a failure. Not an Engineer, so don’t have a clue about the 1’s & 0’s, but do know that this is not just an OWC Issue.


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    can you use both ssd individual? Can you use one drive for the main osx and the other drive as a storage?

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