EDIT: Class 10 SDXC 64GB cards WILL NOT WORK in most if not all Motorola Devices, the HD/MAXX HD included, especially if your device is running 4.0 or higher. Some resources: Motorola DROID RAZR HD - Full phone specifications ^^Link shows the max expandable card is 32GB, along with most other Moto phones, and if you browse to the SGSIII it says up to 64GB, so this info should be somewhat accurate and trustworthy. SanDisk 64gb MicroSd woes ^^Another user from another forum experimenting as well and posting his findings, again, 64GB not working out so well. Basically what I found out was, that the card would work at first, and appear to work. But as time went on, and as I started to use the storage manager in Storage Settings to move items over, it would eventually fail, then tell me the card was blank, which indeed the card would go blank. So the 64GB cards are a no go for the HD/MAXX HD and most likely most other Moto phones as well. This is older, but another freebie: http://forum.xda-developers.com/showthread.php?p=15269669#post15269669 _______________________ EDIT 2: More info in this post here: http://www.droidforums.net/forum/dr...x-hd-class-10-32gb-vs-64gb-3.html#post2339279 And to add, its appears to me that more ppl had better luck with SDXC cards in Gingerbread than ICS, ICS seems to be the one that doesn't care for SDXC cards, just my observation though, I'm thinking, based on some articles, that will change and Jelly Bean will have full support for SDXC and the exFAT files system. ________________________ Ok, here's the purpose of this thread, to see if the larger 64GB SDXC Class 10 cards really do work in the Motorola RAZR HD/MAXX HD devices. I bought one of the 64GB cards a while ago when Amazon had them on sale, and was delighted when I popped the card in and it formatted and worked! As I started to use it, I would notice it would not work properly at some points and had to pop the card out and insert it into my laptop to get media and stuff on the card. Eventually it just stopped working in the phone all together. Here's what would not work:-From Storage in Settings; I was unable to "Manage internal storage" which would automatically transfer all your media to the external card; just would not work -Was unable to use file browser apps (ie; Root Explorer) to manually move files back and forth -Even plugging the phone in via USB cable and using mass storage and media transfer options, I was unable to move stuff back and from to the card from either the internal storage or from my computer My observations after doing some testing (still testing):-Formatting the card in Windows to default, the popping the card in the phone, allowing the phone to format blank SD card = everything would work fine! -Going to keep testing and using and noticing my observations with what I do before hand if it stops working again -So far I can't reproduce the errors again on purpose; though I haven't tried removing the storage without "properly" ejecting the card yet I did find a few resources though that may or may not hint towards the 64GB card NOT working properly in the HD/MAXX HD. In these two sites I found; 32GB card and 64GB card, the compatible phones are listed and for the 64GB card the HD/MAXX HD are not listed. SanDisk® MicroSDHC 32GB Class 10 Memory Card with Adapter - SDSDQUA-032G-A11A SanDisk® 64GB Class 10 MicroSDXC Card with Adapter - SDSDQUA-064G-A11A [There is a compatibility section for each card; note that the HD/MAXX HD are listed for the 32GB card and NOT for the 64GB card; does this hold truth?] So my question is this - ANYONE else with a RAZR HD or RAZR MAXX HD with a 64GB Class 10 SDXC card have any issues at all? <-- Please answer this for me. -If so, what are your observations? So far I was able to get my 64GB working again and its still working, I'll keep this updated if it stops working again and what my observations were before hand.