Mac: All Intel Macs. Unofficial support exists for various PowerPC models running OS 8.6 or later, but OWC cannot guarantee any particular boot support. Please note, PowerPC Macs will definitely not be able to boot external enclosures that have over 2.2TB support enabled. This is a hardware limitation of the computer.
PC: Will boot as long as your BIOS supports booting from the USB 2.0 interface. BIOS support will vary by motherboard and host board adapters.