I haven't heard of this but I want to see what the concensus is. I am upgrading our G3-450 (12gb HD) at work with a Sonnet ZIFF G4-800 CPU, an 80gb additional internal HD and Panther (along with various other software upgrades) My questions is that the instruction sheet that came with the G4-800 CPU says: Important Information for Encoree/ZIF G4 Processor Upgrade Card (700 MHz or, faster), Users Recommendations for users about to install Mac OS X: If possible, update the firmware on every PCI card in your system before you install Mac OS X; in some cases,, your PCI cards may not be compatible with OS X unless you update the firmware. Check the manufacturers' web sites for the latest software. Install Mac OS X before you install the Encore/ZIF G4 card, and .verify it runs properly. This will help to ensure that potential issues will be resolved before you upgrade the hardware.'' Read the Sonnet X Tune-Up and Mac OS X installer Read Me files before proceeding with your Mac OS, X installation. You will regarding system requirements and configuration that may affect you. When installing Mac OS X onto a' hard drive larger than 8GB in capacity, be sure to install OS X in the first partition of the drive, which must be 8GB or smaller. Refer to the Read Me files for more information. Known Issues: Certain 256MB DIMMs (RAM) and certain hard drive models have been reported to be incompatible under OS X when installed in certain beige Power. Macintosh G3 computers. This is not a Sonnet issue. Certain third-party PCI cards, including some cards sold by Apple as upgrades, are not compatible with Mac OS X. If you encounter OS X installation issues, please.remove them and attempt the OS X installation again. Again, this is not a Sonnet issue. I OCR'd this information directly from the sheet, so please excuse any spelling misses. I can't believe that I would have to create an 8gb partion on the 80gb just to install Panther. Can someone back me up??