Michael Fleming

Q: SDXC slot compatibility

Will the SDXC slot on a 2015 MacBook Pro 13inch read the latest UHS-II SD memory cards at 150MB/s or 300MB/s?

MacBook

Posted on Jul 16, 2015 3:49 PM

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Q: SDXC slot compatibility

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  • by ApMaX,

    ApMaX ApMaX Aug 8, 2015 12:10 PM in response to Michael Fleming
    Level 1 (17 points)
    Mac OS X
    Aug 8, 2015 12:10 PM in response to Michael Fleming

    Besides such STANDARD "Bus Speed"

    https://www.sdcard.org/consumers/speed/bus_speed/index.html

     

    is there any Mac supporting also the known as MAXIMUM SPEED?

    https://www.sdcard.org/consumers/speed/max_speed/index.html


    Examples of Maximum speeds for UHS-II cards:


    Lexar 64GB Professional 2000x UHS-II U3 SDXC (300 MB/s read & 260 MB/s write)

    http://www.lexar.com/pro-2000x-sd?category=5286

     

    SanDisk 64GB ExtremePRO UHS-II SDXC Memory Card (280 MB/s read and 250 MB/s write)

    http://www.sandisk.com/products/memory-cards/sd/extremepro-sdxc-sdhc-uhs-ii/?cap acity=64GB

     

    Thanks.

  • by ApMaX,

    ApMaX ApMaX Dec 11, 2015 12:54 PM in response to ApMaX
    Level 1 (17 points)
    Mac OS X
    Dec 11, 2015 12:54 PM in response to ApMaX

    Somebody knows if any current Mac has SDXC card slot supporting UHS-II maximum read/write speeds? Thanks.

  • by Duane,

    Duane Duane Dec 11, 2015 7:56 PM in response to Michael Fleming
    Level 10 (124,018 points)
    Dec 11, 2015 7:56 PM in response to Michael Fleming

    According to About the SD and SDXC card slot - Apple Support, "Mac notebooks use the USB bus to communicate with the SD card slot and have a maximum speed of up to 480 Mbit/s."

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 12:43 AM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 12:43 AM in response to Duane

    Yes, I kow, but that is simply not true. For insance, the iMac or Mac mini (late 2012) SDXC reader is compatible with UHS-II cards (reads/writes them), but at UHS-I speeds (100 Mbps) instead of UHS-II speeds (300 Mbps). Tested in the real-world with UHS-II cards, which have an extra row of contacts (pins) as shown at

     

    A list of UHS-II SD cards, readers, and cameras

    https://www.pretzellogix.net/2014/10/24/a-list-of-all-uhs-ii-sd-cards-readers-an d-cameras/

    https://www.pretzellogix.net/wp-content/uploads/2014/10/uhs-i-vs-uhs-ii.png

     

    Even more, the "Apple - About This Mac - System Reports - Hardware - Card Reader" on such Macs shows "Link Speed: 2.5 GT/s" (250 MB/s), which again is not true. That may be the bus speed, but the Apple SDXC readers in such Mac models do not have the pins to support it, since they do not deliver UHS-II speeds but lower UHS-I speeds.

     

    In summary, the Mac motherboards and port buses may support such UHS-II speeds, but the built-in Apple Mac SDXC readers must have such extra pins, or else will read UHS-II cards with UHS-II speeds.

     

    Somebody knows if any current Mac has SDXC card slot supporting UHS-II maximum read/write speeds? Thanks.

  • by Duane,

    Duane Duane Dec 12, 2015 9:17 AM in response to ApMaX
    Level 10 (124,018 points)
    Dec 12, 2015 9:17 AM in response to ApMaX

    I'm not sure where you are getting your information. The links you provide do not say anything about testing with a Mac.

     

    The system information you posted does not match the information found on my MacBook Pro Retina 15" mid-2014

     

    System InformationScreenSnapz005.png

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 9:31 AM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 9:31 AM in response to Duane

    Thanks, but that is not what I meant:

     

    I said:

    "Apple - About This Mac - System Reports - Hardware - Card Reader"

     

    But you have posted a different component:

    "Apple - About This Mac - System Reports - Hardware - USB"

     

    The former is the Apple Mac built-in SDXC Card Reader, which is what I asked for. The latter is an EXTERNAL card reader connected to a Mac USB port. It is not the same.

     

    I did the testing myself with Mac mini and iMac as described above. So, the question remains:

     

    Somebody knows if any current Mac has SDXC card slot supporting UHS-II maximum read/write speeds? Thanks.

  • by Duane,

    Duane Duane Dec 12, 2015 9:35 AM in response to ApMaX
    Level 10 (124,018 points)
    Dec 12, 2015 9:35 AM in response to ApMaX

    Nope. What I posted is showing the connection to the internal card reader in my MacBook Pro.

     

    The card reader does not show up under Hardware -> Card Reader.

     

    And yes the card reader works just fine.

     

    System InformationScreenSnapz006.png

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 9:47 AM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 9:47 AM in response to Duane

    Well, that is interesting. Then, it seems that laptops and desktops have different internal wiring for the built-in card readers.

     

    In any case, I have found that the Apple specifications are wrong, at least for the Mac mini and iMac described above. They show 2.5 GT/s" (250 MB/s), yet they only have 100 MB/s in real-life tests with UHS-II cards.

     

    Which model/year is your MacBook Pro?

    Could you do some real tests of write/read speeds with UHS-II cards in your MacBook Pro? You can use QuickBench of DiskTools Pro (commercial), or the free Disk Speed Test (BlackMagic). Thanks.

  • by Duane,

    Duane Duane Dec 12, 2015 10:38 AM in response to ApMaX
    Level 10 (124,018 points)
    Dec 12, 2015 10:38 AM in response to ApMaX

    I don't have an iMac with an internal card reader.

     

    I mentioned above ... MacBook Pro Retina 15" mid-2014

     

    If you send me a UHS-II card, I can perform the tests.

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 11:11 AM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 11:11 AM in response to Duane

    Thanks. You said:

     

    - What I posted is showing the connection to the internal card reader in my MacBook Pro.

    - I don't have an iMac with an internal card reader.

     

    But the Mac model is irrelevant. What I asked for is if somebody could check if any Mac can actually read/write UHS-II cards with 300 Mbps speeds in real-world tests.

     

    I do not have UHS-II cards. I tested one before purchase and got the shocking results described above (100 Mbps read/write instead of 300 Mbps). And now I am looking for new Mac models that may have true UHS-II card readers to purchase them. Thus, my question.

  • by Duane,

    Duane Duane Dec 12, 2015 12:08 PM in response to ApMaX
    Level 10 (124,018 points)
    Dec 12, 2015 12:08 PM in response to ApMaX

    You said "Well, that is interesting. Then, it seems that laptops and desktops have different internal wiring for the built-in card readers."

    I replied "I don't have an iMac with an internal card reader."

     

    You said "Which model/year is your MacBook Pro?"

    I replied "I mentioned above ... MacBook Pro Retina 15" mid-2014"

     

    You said "Could you do some real tests of write/read speeds with UHS-II cards in your MacBook Pro? "

    I replied "If you send me a UHS-II card, I can perform the tests."

     

    The OP's original question -> Will the SDXC slot on a 2015 MacBook Pro 13inch read the latest UHS-II SD memory cards at 150MB/s or 300MB/s?

     

    I replied 'According to About the SD and SDXC card slot - Apple Support, "Mac notebooks use the USB bus to communicate with the SD card slot and have a maximum speed of up to 480 Mbit/s."'

    - 480 Mbit/s is 60 MB(yte)/s [assuming 8 bits per Byte]

    - So the answer to OP's question is no. The SDXC slot on the new MacBook Pro can not read the cards at 150 MB/s or 300 MB/s.

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 12:48 PM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 12:48 PM in response to Duane

    Thanks. Such Apple specification should be wrong again. I am sure your MacBook Pro Retina 15" mid-2014 should read at least at UHS-I speeds (100 MB/s), if not UHS-II, because much older Macs do read/write at such UHS-I speed. Clearly, Apple got it all wrong in these specifications. That is why real-world tests are needed. Anyone can do such tests?

  • by Duane,

    Duane Duane Dec 12, 2015 3:06 PM in response to ApMaX
    Level 10 (124,018 points)
    Dec 12, 2015 3:06 PM in response to ApMaX

    The Apple specs that I linked to indicate 60 MB/s and you state that you have tested to 100 MB/s so it would seem that the Apple specs are correct.

  • by ApMaX,

    ApMaX ApMaX Dec 12, 2015 11:57 PM in response to Duane
    Level 1 (17 points)
    Mac OS X
    Dec 12, 2015 11:57 PM in response to Duane

    No, they are not correct. 60 MB/s are not 100 MB/s. In fact, 104 MB/s:

    Bus Speed

    https://www.sdcard.org/consumers/speed/bus_speed/index.html

     

    And as said this is also wrong:

    About the SD and SDXC card slot

    What is the maximum speed that my computer can use when reading and writing to an SD card in the SD card slot?

    Mac notebooks use the USB bus to communicate with the SD card slot and have a maximum speed of up to 480 Mbit/s. Mac desktops use the PCIe bus to communicate with the SD card slot and can transfer data at a faster rate.

    Check the packaging that came with your SD media to determine the maximum transfer rate used by that specific card.

    Determine the maximum speed of your Mac using the System Profiler.

     

    All explained above. Again, real-world tests are needed to truly determine the real read/write speeds.

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