Macintosh OSX on a Traditional Motherboard

Most Apple Macintosh systems prior to the G5 had a native limitation of 137GB supporting ATA interface disc drives. Operating system support for 48-bit LBA addressing begins with OS X 10.2/9.2.2. BootROM support for 48-bit is also a requirement. For further information, see AppleCare Document 86178.

48-bit disc drives attached to systems built prior to OS X 10.2/9.2.2 and without adequate BootROM support will be limited to 137GB. Otherwise, consider the purchase of an Ultra ATA/133 PCI controller card specifically designed for Macintosh computers, available from most retail and online computer stores.

Macintosh OS X also has a coincidental maximum partition size limit of 137GB for volumes using the PC FAT32 file system. This restriction would apply to all types of mass storage (ATA, SCSI, Firewire, etc). See AppleCare Document 107483 for details.

Macintosh OSX on a PCI Controller Card

New controller cards are available that support ATA interface disc drives through their own onboard BIOS and custom Mac OS device drivers. Please see our list of PCI vendors which are known to manufacture ATA controller cards that support Mac OS drives greater than 137GB.

For more background information about 48-bit LBA addressing please visit our overview on this issue. You may also use our Capacity Limitations Walk-Through for 137 GByte limits, as well as other capacity limitations.

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