Please read this document in its entirety before using LeopardAssist.

What's New?

Version 3.0 introduces several new additions to LeopardAssist, and is a complete rewrite from previous versions.

What does LeopardAssist do?

LeopardAssist assists in the process of installing OS X Leopard on PowerPC based Macs, including machines that did not meet the minimum system requirement of an 867MHz or faster processor. It achieves this by temporarily writing a script into the NVRAM of your G4-based Mac. Executed at startup, this script will temporarily force the system to report that a faster processor is installed, allowing the Leopard installer to successfully complete its minimum system requirements check.

This allows Leopard to be installed from unmodified installation media or another bootable device. LeopardAssist handles the interaction with Open Firmware, specifying the target processor speed, the number of physical processors in the system, the desired boot device and any additional startup flags to simplify the installation and configuration process.

Some aspects of LeopardAssist are derived from the article "Faking Out the Leopard Installer with Open Firmware", written by Dylan McDermond for LowEndMac (

How do I use it?

LeopardAssist will run on any G4 or G5 based Mac with a previous installation of OS X Panther 10.3 or OS X Tiger 10.4. Insert or connect your OS X Leopard installation media, ensure you are logged in as an Administrator and follow the prompts in LeopardAssist to prepare the system for installation.

Known Risks & Issues

LeopardAssist has been tested across many different systems and hardware configurations, however it is impossible to accurately test every different possible combination of hardware and software. While all changes made by LeopardAssist are designed to be reversible, the software can not be guaranteed to function correctly across all configurations and is provided on an as-is basis.

Technical Support

LeopardAssist is widely used and supported across many specialist Mac communities, such as the MacRumors PowerPC Macs Forum ( Any questions related to the use, care and maintenance of your PowerPC based Mac and the installation of OS X Leopard can be directed to one of these communities.

In addition, further information about LeopardAssist can be found on the LeopardAssist SourceForge site (