Amazon Customer "Christian"
I routinely use SDXC cards up to 128GB, and this card was unreadable on arrival.  Both of my PCs said it needed to be formatted, and as a last resort I let one of them try (Windows 7/i7with up-to-date SDXC drivers), and it could not format it.  It's on its way back to Amazon.  I'm glad their returns are so easy!