Recently, I have bought an ASUS Transformer Book T200TA with 32GB internal memory and 4GB RAM. To increase the storage, I have added a 64GB microSD card through its slot. The card is identified as a separate partiotion, as it is supposed to do so, and everything is good.

However, I've decided to install software on the microSD card. The writing is very slow, it took 3 to 4 hours to install TeX Live 2012!!! Other installations also take sometime!

Why does this thing happen?

The microSD card brand is Silicon Power Elite Color microSDXC 64GB UHS-I U1 85MBs With Adapter and is formatted with extFAT filesystem.

  • Well, flash storage on such tiny devices is not meant to be fast. It's just meant to be a convenient way to store data and access it from time to time. microSD cards are not designed to be a replacement for real hard drives. Consider them as being similar to a USB stick. You may be better off installing a proper hard drive instead of a Removable storage device.
    – GiantTree
    Aug 20, 2015 at 18:30
  • That's a good point. I can purchase and install a separate hard drive in the dock, but that causes some problem. I have bought this system to use it simultaneously as a tablet, reading ebooks, watching video lectures and taking notes on the go and also as a laptop to do word processing, recording my lectures, and similar things. Aug 20, 2015 at 18:39

1 Answer 1


The ASUS T200TA uses an Intel Bay Trail-T Z3775 SoC (System-on-Chip). The SD card reader is controlled by that SoC.

Unfortunately there are some bugs present, specifically one that affects UHS-1 SD cards. Please see: [USEFUL] Interesting Bay Trail bug list. Possible Wifi/SD card issues...known?

The Z37XX still has that bug, please see bug VLT55: Intel Atom Processor Z3600 and Z3700 Series - Specification Update - May 2015 (PDF)

  • Thanks for the link. It explains much. However, I wonder if there are any workarounds like updating the BIOS, etc.? Aug 20, 2015 at 18:34
  • I think a workaround has already been implemented, otherwise there would be errors acessing the SD card. What I can assume from the description of the error and workaround is that when an error occurs it repeats the access until it works. That might explain the slow access to the SD card.
    – RPAugusto
    Aug 20, 2015 at 18:40
  • The error is still there and no one is going to do sth about that! Copying data from/to my external mechanical hard drive through USB3 is much much faster than a microSD card! Aug 20, 2015 at 18:43

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