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Windows can't read my 8 GB micro SDHC

It can happen that an 8 GB micro SDHC card which works perfectly from a phone fails to work on your PC. When it is connected to a computer using the Windows XP platform, the data on the card cannot be accessed because the computer gets frozen in the process. This happens due to hardware issues. To read the SDHC card, you need a SDHC card reader which will enable the computer to access the information. The most important factor is that the card as well the reader must be formatted to the FAT32 file system to get the rated capacity.


Windows XP can't read my 8 GB micro SDHC. The computer detects the card when I insert it into the integrated card reader, but hangs when I try to open the folder. The same happens when I try connecting my phone to my computer via USB cable.


SD and SDHC cards work in fundamentally different ways. In order to increase the card's capacity, SDHC cards are made to different specifications and use a different file formatting system in order to handle the higher capacity. This means that an SD card reader cannot read an SDHC card. You will need an SDHC card reader.

Tcchnical Explanation:

In the original SD format, the card stored 4096 clusters of up to 512 blocks. Each block contained 512 bytes of information. This gave the card a capacity of 4096 x 512 x 512 = 1 Gigabyte. These cards typically came pre-formatted to the FAT-16 file system with the MBR partition scheme. This meant that any computer or host type device would recognize them through a card reader.

With the advent of high capacity cards the block capacity was increased from 512 bytes to 1024, and then 2048, giving a capacity of 4096 x 2048 x 2048 = 32 Gigabytes. These cards can only be formatted to the FAT-32 file system.

This is why an SD card reader will not recognize the data stream from a SDHC card. The situation is being further complicated because there is now an XC (extended capacity) card on the market which has a capacity of 2 terabytes (2048 Gigabytes) but this is at present being limited to 64 gigabytes by the SD 2.0 documentation.

The first thing you should do when you purchase your SDHC card and SDHC card reader is to format the card to the FAT32 file system otherwise you will not get the rated capacity out of the card. There is no need to defragment it. Doing so will only wear the card out quicker. These cards have a finite life and the more you re-write them the sooner they will wear out.


Thanks to jettibo on the forum for this tip.

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