Ok, so basically I've reaching the end of my patience.... I bough this SD card on amazon : http://www.amazon.ca/Lexar-Platinum-UHS-I-Memory-LSD64GBSBNA200/dp/B008LR284K/ref=sr_1_4?ie=UTF8&qid=1425075338&sr=8-4&keywords=lexar 64gb First my Win 8.1 desktop computer cannot detect that SD card through a SD-to-USB dongle. After messing around and been only able to format it to 64 KB, I finally found out that my laptop with Win7 got a SD slot that can detect the card correctly. So I use this tutorial : https://gbatemp.net/threads/how-to-use-a-64gb-micro-sdxc-in-your-sdhc-compliant-flash-cart.335912/ And format the 64GB on Fat32.....and my 3DS still doesn't detect it. Even my Desktop computer cannot detect neither. It seem only my laptop does.... Could one of you have any clues on what's happening? EDIT : It seem that I've finally made the card working by making it a "primary" partition (my Win8.1 still doesn't want to detect it). But copying root of my old SD card make it lose the CIA. Is there a way to kept everything?