Apple Performa 6400/180 - Manual (Page 225)

Additional Procedures 6500—Software Installation Errors and L2 Cache Identification
These symptoms may appear with any software, installer,
and installation from CDs, floppy disks, Zip disks, or
external hard drives.
Identifying Suspect Units
This problem is caused by a combination of a certain logic
board manufacturer (OPC) together with a certain L2 cache
in a small percentage of Power Macintosh 6500 computers
that fall within this serial number range:
PM 6500 from XB708xxxxx to XB718xxxxx