If you have more than one of the PIV flash chips let me know. I've got a PIV in an A4000T that only works in Z2 mode. I was told that the onboard SCSI is not compatible with the PIV unles the PIV is revision 1.4. Incidently, I believe the 4091 causes issues with running the PIV in Z3 mode. Setting it toe Z2 mode may make this combo work.
