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2013 MBA and SD Card Reader

6377 Views 9 Replies Latest reply: Mar 12, 2014 9:59 PM by Titania1160 RSS
JoshFink1 Calculating status...
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Sep 4, 2013 1:12 PM

I'm hoping someone can help me out here. I have the new 2013 MacBook Air. I purchased a 64GB SDXC card (SanDisk Ultra 64 GB MicroSDXC Class 10 - UHS-1 with Adapter - Model # SDSDQU-064G-AFFP-A)

 

The card is advertised as 30 MB/s write speeds. Which I'm taking as the theoretical max that it will handle. However I'm only getting 10 MB/s writing to the card.


Is is the card or is it my MBA? Does anyone have any real world experience where they are getting faster speeds?

 

I've not seen any hard data only data that says, "Hey, it runs on the USB 3 Bus and can now get up to 5Gb/s"

 

Thanks for the help

 

Josh

  • PlotinusVeritas Level 6 Level 6 (13,615 points)
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    Sep 9, 2013 2:18 PM (in response to JoshFink1)

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

     

    Macs that use the USB bus to communicate with the SD card slot have a maximum speed of up to 480 Mbit/s. Newer Macs use the PCIe bus to communicate with the SD card slot and can transfer data at a much 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:

    1. Choose About this Mac from the Apple () menu.
    2. Click More Info.
      1. Select USB from the hardware section (for Macs that use the USB bus to communicate with the SD card slot).
      2. Select Internal Memory Card Reader and look for the Speed entry.
      or
      1. Select Card Reader from the Hardware section (for Macs that use the PCIe bus to communicate with the SD card slot).
      2. Look for the Link Speed entry. Computers that use the PCIe bus express their speed as GT/s.
  • PlotinusVeritas Level 6 Level 6 (13,615 points)
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    Sep 10, 2013 1:50 PM (in response to JoshFink1)

    youre also trying to write to a micro SD card thru a SD to micro caddy.

  • elie1095 Level 1 Level 1 (10 points)
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    Sep 23, 2013 4:25 PM (in response to JoshFink1)

    There's some inconsistency from Apple on whether the SD slot is connected via USB bus or PCI-E bus. The SD article from Apple mentions "newer Macs" as connecting via PCI-E, but System Profiler doesn't agree, showing it connected to the USB 3.0 bus on the 2013 MBA (my 2012 MBA shows the SD slot as connected to a USB 2.0 bus with max speed of 480 Mb/s).

     

    Also the 5Gb/s speed you're seeing for the SD slot is 5 gigaBITS per second, so divide that by 8 to get gigabytes per second (640 MB/s).

     

    Plot -- the microSD adapter does not affect speed since it's a passive adapter.. It just connects the pins together.

  • PlotinusVeritas Level 6 Level 6 (13,615 points)
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    Sep 23, 2013 4:45 PM (in response to elie1095)

    SD Card Readers in the current MacBook Pros are connected via pcie  NOT however the current 2013 Air

     

     

    You got the other info off Apple which states: Macs that use the USB bus to communicate with the SD card slot have a maximum speed of up to 480 Mbit/s. Newer Macs use the PCIe bus to communicate with the SD card slot and can transfer data at a much faster rate.

     

     

    Im also quite sure the OP was not using a FAST microSD card,....last I recall you cant even find FAST microSD in retail electronics.

     

     

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

    1. Choose About this Mac from the Apple () menu.
    2. Click More Info.
      1. Select USB from the hardware section (for Macs that use the USB bus to communicate with the SD card slot).
      2. Select Internal Memory Card Reader and look for the Speed entry.
      or
    3. Select Card Reader from the Hardware section (for Macs that use the PCIe bus to communicate with the SD card slot).
    4. Look for the Link Speed entry. Computers that use the PCIe bus express their speed as GT/s.

     

     

    Class 10 cards should get transfer speeds of at least 10MB/second, while cheaper microSD cards have as low as 4MB/second transfer speeds. Transfer speeds will also depend on the mac as older MacBooks treat the SD card slot as a USB 2.0 connection, while newer ones use the PCIe bus to connect to the SD card slot.

     

    real-life testing gets about 10MB/second transfer speeds. Copying a ~600Mb file  took right around one minute. That’s slower than transferring to  USB 3 external hard drive (copying the same file took around 40 seconds)

  • elie1095 Level 1 Level 1 (10 points)
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    Sep 23, 2013 5:17 PM (in response to PlotinusVeritas)

    Thanks for the reply. I'm going to guess that the Apple article (http://support.apple.com/kb/HT3553#4) lists "new Macs" as using the PCI-E bus when they should've specified "new MacBook Pros" and maybe iMacs. I haven't been able to find any definitive source though that says that the Macbook Air SD card reader uses USB, while the Pro uses PCI-E.

     

    What I did find:

     

    If you can find any source that says that the Macbook Air uses USB and Macbook Pro uses PCI-E, could you please link?

  • PlotinusVeritas Level 6 Level 6 (13,615 points)
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    Sep 23, 2013 5:26 PM (in response to elie1095)

    "Newer Macs use the PCIe bus" is off Apples own site.   however this generalization doesnt seem to cover the Air specifically as per the 2013, unless info to the contrary (which I can find nowhere, not even on my own 2013 AIR) pops up.

     

    http://support.apple.com/kb/ht2838

     

     

    http://support.apple.com/kb/HT3553

     

     

     

     

  • Titania1160 Calculating status...
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    Mar 12, 2014 9:59 PM (in response to PlotinusVeritas)

    Simply for information: My New Macbook Pro Retina (Currently shipping model, FULLY upgraded) 13.3" shows the card reader as being slaved to the USB 3 BUS with a 5GB/sec transfer rate.

     

    I am wondering if the Macbooks apply or if it's a 15" retina feature only in the Macbook line. Considering the focus on PCIe interconnect, I am unsurprised that the PRO would use a PCIe bridge to card slot.

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