The Raspberry Pi's bootloader, built into the GPU and non-updateable, only has support for reading from FAT filesystems (both FAT16 and FAT32), and is unable to boot from an exFAT filesystem. So if you want to use NOOBS on a card that is 64GB or larger, you need to reformat it as FAT32 first before copying the NOOBS files to it.

The standard formatting tools built into these operating systems are able to create FAT32 partitions; they might also be labelled as FAT or MS-DOS. Simply delete the existing exFAT partition and create and format a new FAT32 primary partition, before proceeding with the rest of the [NOOBS instructions](noobs.md). On a Mac, this means using the command-line `diskutil` program.

The standard formatting tools built into Windows are limited, as they only allow partitions up to 32GB to be formatted as FAT32, so to format a 64GB partition as FAT32 you need to use a third-party formatting tool. A simple tool to do this is [FAT32 Format](http://www.ridgecrop.demon.co.uk/guiformat.htm) which downloads as a single file named `guiformat.exe` - no installation is necessary.