Mac Pro 5,1 won’t boot

if you choose to use Open Core alternate boot loader, Best Practice is to have an unmodified bootable drive on hand to rescue yourself. Then if things go badly for any reason, you SHOULD be able to elect the 'Plain' drive using the Mac built-in Startup Assistant/ Boot-Picker, and proceed to get back to MacOS (and try again, if desired).

the simplest thing your Mac can do is boot while you hold the Option key. this invokes the startup manager/Boot-Picker from the Mac's ROM. No drives need to be working at all to get the gray screen, and if any drive appears bootable, an icon will be added over the next several minutes.

Hi,

As Grant suggest, you need to connect wired keyboard, instead of wireless.

<< So I discovered that once you update firmware to install a Metal graphics card, the “option” key does not work any more! >>

That is NOT correct. I have three of those Mac Pros and the Option key works exactly the same before and after Firmware upgrade. it is not the FIRMWARE Upgrade that causes your grief.

BUT: the keyboard must be connected to a port DIRECTLY on the chassis (not on a display or other Hub) to be available at startup.

Some windows keyboards swap which key is Alt/option, usually with the Control key next to it.

¿Does you metal graphics card support Mac boot screens? many that support Metal do not support boot screens, unless explicitly modified to do so. ¿Does you new graphics card option-Boot with Mojave? it should!

rzero Said:

"Mac Pro 5,1 won’t boot: I have a Mac Pro 5,1 that’s was running Mojave. I was attempting to up date to Monterey using Opencore. I installed the assets and next I was to restart zapping the PRAM! After a few attemps, my computer now starts up and then shuts itself down before any boot screen shows up! Any solutions out there??"

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Troubleshooting Mac Boot:

A. Black Mac Screen:

Go Here: If your Mac doesn't Turn On or Start Up - Apple Support

Using External Devices: Try Resetting the SMC and NVRAM, but this time, using an external keyboard. Connect an external monitor and see if you get an output.

B. Mac Power Issues:

Try a New Charger:

If it is currently charging from a charger, then use a new charger:

• Power & Cables - Mac Accessories - Apple - Select "Mac Compatibility" on the left
• Find the right power adapter and cable for your Mac notebook - Apple Support

C. A Few Links to Refer to Power:

• If your Mac doesn't Turn On - Apple Support

• How to Turn your Mac On or Off - Apple Support

• About Mac Notebook Batteries - Apple Support

• Charge the MacBook Pro Battery - Apple Support

• If your Mac Battery won't Charge - Apple Support 

Hi,

You should to create bootable OpenCore patched macOS installer on USB memory on another Mac.

My Video card is HD5770, not Metal video card, running Ventura without no problem.

You should remember that you must using latest OpenCore Patcher.

Oh well, we shouldn't discuss about this here.