Riku wants to use one of the GND pins for CMD or DAT0, but as soon as a regular SD card is inserted the CMD or DAT0 is tied to GND and the SoC will no longer be able to communicate with the flash. Additionally, pin #8 and #9 are usually tied to DAT1 and DAT2.. granted, those pins are not essential for the non-parallel transfer modes and I have no idea whether the 3ds SD card reader makes use of them.As on a document some pages before at least 2 Pins are marked with nc.