I recently got Catalina working on the P6T Deluxe V2. My main problem was constant resetting during the install. I eventually figured out by reading the install logs off the EFI drive that the reset was intentional and part of the installation process. I kept rebooting into the the same install drive and the install would start over again. I figured out that after the reboot during install, I had to then select the "Preboot" drive on the next install so installation would finish. See if this works for you.
No luck, I Only have a "Boot FileVault Prebooter from Preboot" disk option and it's High Sierra.
I'm trying to keep both and the procedure I tried so far is:
1. In Disk Utility chosen HSSystemSSD, partition, add volume.
2. Restarted the system from USB (F8 + select USB) didn't start the Installer.
3. Restarted the system normally (EFI partition) and loaded Clover was the USB version 5102 (system is 4769). first anomaly.
4. available disk to select was only USB Catalina installer.
5. ConfiguredClover options as Args: cpus=1 dart=0, SMBios MacPro6,1 on both parameters, Graphics Inject ATI + Deinit , ( dough my system config.plist are in place but card was recognised as rx-480..changed em anyways.)
6. Started the installer (started fine)
7. Installed Catalina on new volume.
8. At restart removed USB installer as it was still showing only 1 disk as as at step #4.
9. Available disks are the usual plus "Boot macOSInstall from catalina"(new volume's name) but no new "Boot FileVault Prebooter from Preboot" so I chosen "Boot macOSInstall from catalina".
10. During booting, progress bar kept progressing until screen wasn't showing anything anymore (second anomaly ) but it was eventually installing it as after a 10 minutes the system restarted.
11. At Clover screen still no new "Boot FileVault Prebooter from Preboot" disk, but"Boot macOSInstall from catalina" changed into"Boot macOSInstall from catalina-Data". ( this is where I got stuck as every body before "select the Preboot" drive suggestion.) and now I thought that the new "Boot FileVault Prebooter from Preboot" would be there.
Well it's not. So I'm still stuck at the same point even with the new rx-580 card.
It could be due to dual System and I still haven't tried to fresh install just Catalina, or to update High-Sierra to Catalina directly as I need both, but I made a back-up and I'll give it a try.
Any suggestions to keep both? maybe install Catalina on a separate drive instead that on a new volume on the same drive?
