Quote:
Originally Posted by Shaleen77
Hi All,
Also, all the 64GB class10 cards seem to be sdxc. One forum post did mention that they have used sdxc with the LG G Pro with no issues. Some have mentioned Kingston cards having higher speeds. Anyone used Kingston microsd cards ?
I would also like to understand the diff between FAT32 and exFAT. Maybe that is why some cards don't work in dome devices. Could someone shed some light on this, please.
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(Whenever I mention SDXC or SDHC below, that applies to micro-SDXC/micro-SDHC as well.)
I have had reason to experiment with a 64GB SDXC card to my Motorola Xoom that only supports 32GB SDHC. And it is possible to use the card by only accessing the card from a computer using a simple card reader and reformatting it to FAT32, as long as you don't attempt to format the card using the standard Windows utilities.
More details:
The standard for SD-cards specify that the max size of a SDHC-card is 32GB. So if the specification for a device mention that is supports SDHC, then that means that you only can be certain that it supports 32GB. And typically formatted as FAT32.
The standard dictates that there can be no SDHC cards larger than 32GB. If you need bigger card you have to use a SDXC card instead. 64GB or 128GB for instance. They are typically formatted using exFAT.
Not all devices have support for SDXC and exFAT so they don't explicitly support cards larger than 32GB.
The standard is "enforced" by the formatting utilities in Windows and also often by the firmware in devices, when the card is mounted from a computer. You can't format a SD-card that is larger than 32GB as FAT32 using the Windows tools. Also the card will sometimes become corrupt if the card is bigger than 32GB, formatted as fat32 and is inserted in the device and the device is mounted in Windows over USB.
Some (most?) SDXC cards has the exact same contacts as the older SDHC cards. And it is *usually* possible to format those cards to use FAT32, as long as you don't us the Windows utilities, and then use them on older devices that don't explicitly support SDXC. So there really is no technical reason for limiting the size of SDHC-cards to 32GB. It is more a marketing and sales thing, than a technical limitation. However FAT32 is less efficient and more wasteful than exFAT on larger cards, so if you can use exFAT, then that should be used. Or anything but FAT32...
There are plenty of 3:rd party utilities to reformat a SDXC card from exFAT to FAT32, and after that many devices that only says they support SDHC will happily let you use the reformatted 64GB SDXC card.
But if you attempt to access the card from a computer while it is inserted in the device, the card may become corrupted. Actually it seems that the firmware "fix" the card by reducing it to 32GB. And you loose data.
I was very confused before I figured out what was happening. However it is still possible to access and write to the card from Windows as long as you use a simple SDHC or SDXC card reader. I say simple, because if it is some form of smart device, then the firmware may attempt to "fix" it by reducing the size to 32GB.
So even if your device only support 32GB SDHC, you may be able to use a reformatted bigger SDXC-card. As long as you don't access the card from a computer while it is in the device. I have no experience with anything but a 64GB SDXC-card. I have no idea if a 128GB SDXC-card can be used the same way. Please report if you have tested it.
I've successfully used a 64GB Sandisk Class 6 card in my XOOM for a few years now...
http://en.wikipedia.org/wiki/Secure_Digital