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I'm considering buying an ExpressCard 34 USB 3 adapter for my 2010 MacBook Pro 17" so that I can benefit from USB 3.0 speeds when used with my Samsung S2 1 TB USB 3.0 superspeed drive.

However, such Mac OS X compatible ExpressCard 34 USB 3.0 cards are scarce:

  • Lacie make a ExpressCard 34 USB 3.0 but the Mac OS X driver they supply only supports their own USB 3.0 drives, not other brands of drives. Not really true USB 3.0 compatibility, rather proprietary. Sure, it uses the USB 3.0 physical interface, and runs at USB 3.0 speeds perhaps, but it is proprietary. USB 3.0 is a standard, a universal standard, hence the name. Lacie do point out that it's only for their drives on their literature online, but you have to look carefully, it's not a headline point.

  • CalDigit also make a ExpressCard 34 USB 3.0 which looks a little more promising than the Lacie because although "optimised" for their drive, they don't say it won't work for other drives, but nor do they say it will work at USB 3.0 speeds for other drives.


  1. Are there any other brands of ExpressCard 34 USB 3.0 cards, but which can work with any brand of USB 3.0 hard drive in Mac OS X at (or at least a few Gbit/s) USB 3.0 speeds? Have you tried them? Or is there real benchmark data?

  2. Have you tried the CalDigit card and does it run at (or at least a few Gbit/s) USB 3.0 speeds in Mac OS X with non-CalDigit brand drives?

  3. Do these cards and drives also work at USB 3.0 speeds (or at least a few Gbit/s) when booted via Boot Camp into Windows?


Updated question to say "near to" USB 3.0 speeds as I'm informed ExpressCard does not support 5 Gb/s but 2.5 Gb/s. 2.5 Gb/s is far better than 480 Mbit/s of USB 2.0.

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closed as off topic by Sathya Apr 19 '12 at 16:53

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There is a review here that indicates the CalDigit supports other drives at USB3.0 speeds in MacOS. It is encouraging but not conclusive as the author refers to a Calvary USB3.0 dock and not common-all-garden big name USB3.0 drives such as Samsung, Seagate, WD, IBM etc. – therobyouknow Sep 5 '11 at 18:52
up vote 1 down vote accepted

Looks like the CalDigit is the best option - there is no deliberate proprietary lock down with their USB 3.0 cards for Mac/Windows.

I emailed and then telephoned their support in the US, (from the UK!):

  • They have tested it on other brands as well as their own. They sensibly say cannot guarantee every drive will be compatible, but nor are they saying other brand drives won't work.

  • It is possible that a given USB 3.0 drive will work with the CalDigit ExpressCard 34 SuperSpeed USB 3.0 on the Mac at speeds at a large fraction or meeting USB3.0 speeds i.e. 1 or more/several Gb/s or at least far higher than USB2.0.

  • The only instances they are aware of are where a bus-powered very large capacity i.e. >1Tb (at time of writing) drive draws too much power due to the large number of platters being spun. (I don't work for CalDigit).


With pleasure, I can report that the Samsung S2 1Tb 1.0 Tb USB3.0 Superspeed drive does work with the CalDigit ExpressCard 34 USB3.0 Superspeed with MacOS Lion 10.7, at noticeably faster speeds than when it is plugged into one of the Mac's built in USB2.0 slots. When same Mac is booted into Windows 7 64 bit pro via bootcamp, the drive also works. CalDigit supply a Apple MacOS driver and Windows driver for their card, downloadable from their site,

So, in conclusion, it looks promising that CalDigit's CalDigit ExpressCard 34 USB3.0 Superspeed will work with at least several brands of hard drive. That was their intention to implement USB3.0 in such a way to support any USB3.0 drive, though they cannot test every drive manufacturer due to time and resources. Once again, I don't work from them. Though I am pleased with their approach rather than Lacie's locked down approach with Lacie's MacOS driver only supporting Lacie's brand.

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There aren't any ExpressCard USB adaptors that run at USB 3.0 speed, because the maximum data transfer rate of ExpressCard is 2.5 Gbit/sec, while USB 3.0 is 5 Gbit/sec. (ExpressCard 2.0 matches USB 3.0 for speed, but your MacBook Pro doesn't support ExpressCard 2.0 as far as I know.)

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Cardbus does not support USB 3 but ExpressCrad does. There are a number of makers – Dave M Sep 5 '11 at 20:46
@Mike Scott, I appreciate that the bus might not achieve full speed, but I would think that the speed would be much higher than USB 2.0 rate of 480Mbit/s still, surely? If the limit of ExpressCard is 2.5Gb/s I would be happy with USB 3.0 achieving 2.5Gb/s or if overheads, then 2.0Gb/s. And if so, I count that as the benefit I want to achieve as much higher than 480mbit/s. – therobyouknow Sep 5 '11 at 21:18
@Dave M Perhaps you would like to share with us who these makers are of MacOS compatible USB3.0 express cards? – therobyouknow Sep 5 '11 at 21:21
@Mike Scott, how do you know that the MacBookPro 2010 does not have ExpressCard 2.0? Definitive source? (I'll certainly accept this if it's true but please cite references). – therobyouknow Sep 7 '11 at 22:54
@Rob, the Wikipedia article on Expresscard 2.0 says "ExpressCard 2.0 products are expected to be in the market in late 2010". The 2010 MacBook Pro models came out in April 2010, much too early for ExpressCard 2.0. Also, the specs for the machine say "ExpressCard/34" not "ExpressCard 2.0". – Mike Scott Sep 8 '11 at 6:25

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