Thank you, Richard, I'm sad to say, searching MacRumors' site using the term "Sierra, High Sierra, and Mojave for unsupported Macs" yields nothing. However, thank you, I see that I'm at a dead end so must pursue some other solution. Sad to abandon a dogonne good functional Mac Pro for lack of security support.Hello, Louis. There was a discussion long time ago about SIP and Dosdude1’s patcher. Dosdude1’s patcher disables SIP in order for the macOS to work. If one enables SIP on such a patched Mac, the Mac won’t work. One can read the threads for Sierra, High Sierra, and Mojave for unsupported Macs in MacRumors. Hope this helps explain why SIP is disabled for you.