MacPro3,1 Startup Manager (or OpenCore boot picker) issues

[nekton1]

Since Monterey 12.2 and even more so with 12.3 betas, the cMP3,1 listed below has been having Startup Manager OpenCore boot picker problems using a USB booter/installer. The main indicator of the problem is that pressing the Option key at start-up does NOT display the Startup Manager screen while just booting normally without pressing Option DOES display the Startup Manager OpenCore boot picker where I see three icons indicating an internal boot SSD on a Highpoint 7101A, the EFI partition of the USB installer, and the USB installer OS install partition. The USB installer has been created in three different ways by either using the open core patcher to download the OS from Apple or using the MDS utility or manually using python from the Apple catalog. Three different USB sticks have been used as well as two versions of the patcher (0.42 and 0.43n). The problem is always the same whichever USB installer is used.
If I click the OpenCore boot picker USB EFi boot partition as normal, the Mac starts to boot from the USB (can see flashing LED) with the progress bar moving along but ALWAYS stalls half way. The VERY odd thing is that if I click the OpenCore boot picker OS install partition instead of clicking the EFI partition, in about 1 of 10 start-ups the system progresses to the first macOS install setup screen and I can successfully install Monterey 12.2. This never works with 12.3 betas. In the remaining 9 of 10 startups the system install progresses to half way and then reboots over and repeats without end.
I have tried resetting NVRAM between install attempts; I've tried SMC resets using both disconnected power cable method and on-motherboard reset microswitch but nothing has fixed the odd Startup Manager OpenCore boot picker behavior.
At the moment the cMP3,1 is running 12.2 normally and it starts-up and shuts-down as expected.
I'm wondering what the cause of the failure to display the Startup Manager when pressing the Option key might be. Perhaps the boot rom in this "old lady" is on its last legs?
Does anyone have an idea?
Just FYI, I have created USB booter/installers for various unsupported Macs since the earliest days, so this is a procedure that I am very familiar with.

 

[joevt]

You're using an RX580 so it's not possible to see the Apple Startup Manager. Maybe you're looking at the OpenCore boot picker?

 

[nekton1]

You're using an RX580 so it's not possible to see the Apple Startup Manager. Maybe you're looking at the OpenCore boot picker?

Correct but that still does not explain the odd behavior I see where I can NEVER get to the second OS installer stage of the boot picker after selecting the USB installer EFI partition, but if I click the OS installer partition of the boot picker without clicking the EFI partition first, I can get the install to proceed normally in about 10% of install attempts.

 

[nekton1]

Has anyone got a link to a working GOP vbios for the Sapphire Nitro+ 8 GB DDR5 GPU with the Device ID 67DF and Subsystem ID E366?
The VGA bios ROMs at TechPowerup are all for PC as far as I can see.

 

[qball7]

I'm also having (from what I can tell is) the same problem, with the same configuration.

This also happens no matter what version of macOS I try; I've tested 12.0.1, the latest Mavericks, and the latest Big Sur. This is with OCLP 0.4.2.

It's worth noting that, when trying this against a clean drive, that the installer isn't actually placed there; neither the native Apple boot manager (nothing loads; the machine powers off immediately when prompted rather than the extended off anything loaded makes it require) nor the OpenCore one seem to recognize anything's there.

No installer logs are dropped onto the drive, which makes figuring out what's going on rather tricky; the OpenCore logs have vanishingly little to say about why the installer fails to work. However, what I can remember from the logs are somewhat suggestive of the data copied unable to be verified.