Hi there,
SDSDX3- is the former version, this model was updated to SDSDX- , the main difference is that the new SDSDX- has the UHS-I mode enabled, that means that your camera will be able to reach the max. write speed of 30MB/s when working in UHS-1 mode.
These are the different cards:
SDSDX3-032G-A31 : SDHC Extreme Class-10 32GB
(this is only Class-10, can not work under UHS-1 mode)
SDSDX-032G-X46 : SDHC Extreme hd video Class-10 (UHS-1 enabled) 32GB
This card will work as a Class-10 offering a min. write speed of 10MB/s, will get up to 30MB/s when working on UHS-1 mode.
Hope this helps to clarify.
