Installing macOS Mojave 10.14 and performing Mac Pro 5,1 Boot ROM update

You need to update Mac Pro 5,1 Boot ROM to version 144.0.0.0.0 in order to install macOS Mojave 10.14 and newer unsupported systems like macOS Catalina 10.15, macOS Big Sur 11, macOS Monterey 12, macOS Ventura 13, macOS Sonoma 14 and macOS Sequoia 15.

Please check your Boot ROM version by following these steps: How to identify my Mac Pro model and Boot ROM?

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.

If you have NVIDIA card make sure to have the latest Web Driver driver installed which can be downloaded from Drivers page, otherwise installer would complain about Metal support or FileVault enabled: My graphics card is Metal capable, but macOS Mojave installer still complains about lack of Metal support.

If your current card does support High Sierra, but doesn't support Metal (like factory installed NVIDIA GeForce GT120 512 MB, AMD Radeon HD4870 512 MB, AMD Radeon HD5770 1 GB or AMD Radeon HD5870 1 GB) and your new card is too new to have High Sierra support (like RX5000/RX6000 series), then you need a helper card. Best would be to get some cheap HP GeForce GT630 2 GB (the one with DVI and 2x DisplayPort) or DELL GeForce GT640 1 GB/GTX645 1 GB for PC (doesn't need to be flashed with Mac rom) or any Radeon RX460/RX560. Then post updating the Boot ROM you no longer need it.

If you plan to make a clean installation of macOS Mojave, make sure your partition is formatted as APFS filesystem and using GUID Partition Map.

It's also recommended to perform Boot ROM update even if you plan to stay on older macOS version like High Sierra or older.

IMPORTANT: Make sure to run Mojave installer directly from High Sierra, not from bootable USB stick. Otherwise it won't detect Metal properly.

Step 1 You need to start from macOS High Sierra 10.13.6.   To obtain a full copy of macOS Mojave 10.14.6 image you need to download macOS Mojave patcher:   http://dosdude1.com/mojave/#downloads   Click Direct or Mirror link to start downloading.
Step 2 Unpack and double-click patcher icon to launch it.
Step 3 Click Open button. If macOS is blocking it you need to unlock it in System Preferences -> Security & Privacy -> General pane by clicking Allow button.
Step 4 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.
Step 5 From Tools menu choose Download macOS Mojave...
Step 6 Click Yes button to start downloading macOS Mojave image.
Step 7 Click Select Save Location button to save macOS Mojave image file on the desktop or choose your own location.
Step 8 A full copy of macOS Mojave 10.14.6 installer will be downloaded directly from Apple's servers.
Step 9 Click Not Now button and close the tool. You can now launch macOS Mojave installer directly from desktop or from location you've choosed.
Step 10 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.
Step 11 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.
Step 12 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.