Retina MBP SDXC Reader Info

Discussion in 'MacBook Pro' started by Rofflesaurrr, Aug 10, 2012.

  1. Rofflesaurrr macrumors newbie

    Joined:
    May 2, 2012
    #1
    Just in case anyone else was wondering...

    The integrated SDXC card reader on the new MBP is USB 3.0 enabled. The Intel HM77 provides 4 USB 3.0 ports. 3 are external, the 4th is used by the reader. I got read speeds of 77MB/sec with a Sandisk Extreme 95MB/sec card.

    I'm going to purchase a rMBP online, but I could not find any info on what bus the card reader was running on, so I went to Bestbuy to find out. :)
     
  2. innerpurpose1 macrumors newbie

    Joined:
    Jun 14, 2012
    Location:
    Oakland, CA
    #2
    Does this mean that one can use a SDXC card on the new MBP Retina and have comparable speeds to the internal flash drive? I'm wanting to put pics and music on the card and get a 256gb drive instead of spending the extra money for the 500gb drive.
    Thanks for the help!
    Graham
     
  3. Rofflesaurrr thread starter macrumors newbie

    Joined:
    May 2, 2012
    #3
    The SSD in the new Retina Macbook Pro averages speeds of 400-500MB/sec. The best SDXC cards only achieve read speeds of around 100MB/sec at most. Write speeds can be slower. However, a SDXC card on a USB 3.0 reader will usually have better overall performance than a conventional 2.5" internal hard drive. So yes, you could put pictures and music on the card and use it as a secondary storage media. I just wouldn't reccomend it if you're going to be doing a lot of writing to the card. Choose a quality card like a Sandisk Extreme or Lexar Professional. Most of these cards use SLC NAND (more write cycles) and have better wear leveling algorithms.
     
  4. JayMBP macrumors regular

    Joined:
    Apr 25, 2011
    Location:
    Surrey, BC
    #4
    I'm actually having problem with my rMBP's reader.

    It seems to top at 20MB/s. And when I put the same card (Sandisk UHS-1 SDHC) in a USB3.0 reader, I get almost at the rated speed (45MB/s)

    I'm getting some other SD cards next week and I will try them out.
     
  5. retinarob macrumors regular

    Joined:
    Jul 26, 2012
    Location:
    VA
    #5
    Glad I saw this considering I just filled out my backer survey for a NiftyDrive :D
     
  6. terraphantm macrumors 68040

    Joined:
    Jun 27, 2009
    Location:
    Pennsylvania
    #6
    The reader may be connected by USB 2.0 internally.
     
  7. JayMBP macrumors regular

    Joined:
    Apr 25, 2011
    Location:
    Surrey, BC
    #7
    So, are different rMBP having different routing?

    On Anandtech's test, they clearly showed that the reader was capable of handling speeds near 100MB/s

    On a further checking to system info, it shows the reader is "2.5GT/s".

    I'm assuming that the card reader is connected to the PCI-E bus directly hence the use of "GT/s"?
     
  8. terraphantm macrumors 68040

    Joined:
    Jun 27, 2009
    Location:
    Pennsylvania
    #8
    Okay, I didn't notice that part of anandtech's review, and I didn't have my laptop nearby to check. Not sure what to say then - I don't have any SD cards fast enough to test, nor do I have a USB 3.0 SD reader.

    I don't know if it's connected directly to the PCIe bus though. I kinda doubt it. The IvyBridge CPUs have 16 lanes total. 8 of them are going to the GT 650M, and 8 of them are split between the two thunderbolt ports. That doesn't leave any PCIe lanes for other peripherals.
     
  9. Tobias Funke macrumors 6502a

    Tobias Funke

    Joined:
    Apr 3, 2012
    #9
    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.

    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.

    From Apple website.

    CLICKY
     
  10. terraphantm, Aug 13, 2012
    Last edited: Aug 13, 2012

    terraphantm macrumors 68040

    Joined:
    Jun 27, 2009
    Location:
    Pennsylvania
    #10
    Hmm, I guess there must be an extra PCIe controller somewhere in there. Or apple is somehow able to use some circuitry to turn 1 PCIe 3.0 lane into 4 PCIe 1.0 lanes. Or something along those lines.
     
  11. Rofflesaurrr, Aug 13, 2012
    Last edited: Aug 13, 2012

    Rofflesaurrr thread starter macrumors newbie

    Joined:
    May 2, 2012
    #11
    All 3 USB 3.0 ports and the card reader are connected to the same xHCI which has a 2.5GT/s link to the PCH. The USB 3.0 controller is now integrated into the PCH. It is not a separate 3rd party controller connected via a PCIe port. The Intel HM77 PCH also does not contain any PCIe 3.0 lanes. The only PCIe 3.0 lanes are provided by the CPU itself for the GT650M graphics and Thunderbolt.
     
  12. Marx55 macrumors 68000

    Joined:
    Jan 1, 2005
    #12
    The maximum speed is the lowest between the bus and the reader. The bus may be great, but if the reader does not deliver, the latter is the maximum speed. Someone has real-world tests?
     

Share This Page