Installing macOS Mojave 10.14 and performing Mac Pro 5,1 Boot ROM update
You need to update Mac Pro 5,1 Boot ROM in order to install macOS Mojave 10.14 and newer unsupported systems like macOS Catalina 10.15 or macOS Big Sur 11.
Updating Mac Pro 5,1 Boot ROM also:
- enables APFS filesystem support
- adds support for PCI-Express 2.0 (5.0 GT/s link) for all PCI-Express 2.0 or faster cards instead of much slower PCI-Express 1.1 (2.5 GT/s link)
- adds boot support for NVMe drives
- fixes critical CPU security bugs like Spectre & Meltdown etc.
We recommend performing Boot ROM update and macOS Mojave installation with no other PCIe cards installed and a SATA drive connected to one of the internal drive bays. If your macOS High Sierra partition is still running HFS+ filesystem it will be automatically converted to APFS after macOS Mojave installation.
Unpack and double-click patcher icon to launch it.
Click Open button. If macOS is blocking it you need to unlock it in System Preferences -> Security & Privacy -> General pane by clicking Allow button.
Ignore the warning by clicking OK button. We are using this tool just to obtain a full copy of macOS Mojave installer from Apple's servers since it's no longer possible to download it from the AppStore.
From Tools menu choose Download macOS Mojave...
Click Yes button to start downloading macOS Mojave image.
Click Select Save Location button to save macOS Mojave image file on the desktop or choose your own location.
A full copy of macOS Mojave 10.14.6 installer will be downloaded directly from Apple's servers.
Click Not Now button and close the tool. You can now launch macOS Mojave installer directly from desktop or from location you've choosed.
macOS Mojave installer will be launched and you will be presented with instructions on how to update Mac Pro Boot ROM.
Click Shut Down button to turn off Mac Pro.
Press and hold power button as long as you see power LED blinking and hear some loud tone.
Firmware update process will be started. Do no turn off your computer at this moment. Superdrive tray will be ejected and you might see just gray screen without any progress bar.
As soon firmware update is completed the computer will turn off and then back on automatically.
As soon Mac Pro reboots in normal mode, you will be presented with macOS Mojave installer welcome screen. You can now perform the installation.
If you plan to install macOS Catalina 10.15 or later then you can skip macOS Mojave installation. It was only needed to update Mac Pro Boot ROM.