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

Performance testing the new Accelsior E2 simply consisted of testing the eSATA transfer speeds alone, both in system and Helios to make sure they matched which they did.  Detailed performance of the Accelsior alone is available in our Accelsior Review, just as PCIe performance, via Thunderbolt, is available in the OWC Helios review. For our tests, we used two Intel DC S3700 800GB SSDs in RAID 0, both of which we had reviewed previously as well.

OWC Accelsior E2 With Intel DC S3700


ATTO Disk Benchmark is perhaps one of the oldest benchmarks going and is definitely the main staple for manufacturer performance specifications. ATTO uses RAW or compressible data and, for our benchmarks, we use a set length of 256mb and test both the read and write performance of various transfer sizes ranging from 0.5 to 8192kb. Manufacturers prefer this method of testing as it deals with raw (compressible) data rather than random (includes incompressible data) which, although more realistic, results in lower performance results.

INtel DC S3700 RAID 0

RAID 0 performance of 783MB/s read and 761MB/s write is an excellent start and was unexpected through eSATA to say the least.


Crystal Disk Benchmark is used to measure read and write performance through sampling of raw (0/1 Fill/compressible) or random data which is, for the most part, incompressible. Although both are very close, we provide compressible results on the left with incompressible on the right below:

OWC Accelsior SSD CDN 0FillOWC Accelsior SSD CDN RandomTypically, we might see lower test results in Crystal Diskmark, however, these are a bit lower than expected.  This could be a result of the storage medium used which has quite a few hours of testing under their belt (Intel SSDs).


We elected to conduct Anvil Storage testing with 100% incompressible data just to give all a good look at the Accelsior at its best.  Full identification of the system and drives in use is available on the bottom left and right of the result.

OWC Accelsior E2 Anvil Testing


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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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