MP5,1: What you have to do to upgrade to Mojave (BootROM upgrade instructions thread)

[Guest tsialex]

Please fully read this first post, you will probably find that you have one or more problems described into the various notes below.

 

Mojave will only install if you have upgraded your BootROM to the current release and your Mac Pro have a Metal capable GPU*.

 

If you are trying to install Mojave on a Mac Pro 5,1 (early-2009 cross flashed with MP5,1 firmware, mid-2010 and mid-2012), you have first to upgrade your BootROM to version MP51.0089.B00 and to High Sierra 10.13.6, then...

 

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Source: MacRumors