
That external drive may not be visible to BIOS but it will be visible to OS Kernel. In your case, as mentioned in my first post, you probably need to boot off the onboard SATA/IDE in the first place, load bootloader, load kernel, and mount / from external USB drive. This way we may leverage UEFI standard to boot from a controller/device that is unknown to BIOS, either having Clover directly as the hardware firmware, or some glue that would boot off the unknown hardware and then launch Clover from a partition. BIOS UEFI may allow firmware boot for a card but not for a device. But PCI controller may be treated different than is child devices (i.e. If both are possible then we have perfect situation (we talk about device firmware in that case). I am not sure if PCI-E controller card (may provide UEFI firmware) is the same as external USB device (uses onboard USB controller that already is the PCI-E card itself). In this scenario we may enforce standard UEFI firmware boot, even if the card is not supported by BIOS, but as standard PCI-E it may expose the firmware, so the firmware then would detect a drive and chainload the boot from EFI partition located on its child device. In that case we have small generic "glue" firmware loaded into the Controller that would allow it to boot of the disk, even if the controller is not visible to the BIOS. Some sort of Controller "glue" firmware that would UEFI boot the unknown device for BIOS and launch the Clover from EFI partition.That would imply the controller would have to load the firmware from a device and provide it as its own firmware to the BIOS. While UEFI firmware on the controller seems to be a standard, I am not sure if UEFI firmware on a disk is possible (especially when BIOS does not see the controller in the first place).


Here controller is a PCI-E card, while device is a disk drive.

There are several configuration files, the ones starting with config-12 are for Monterey and the ones starting with config-13 are for Ventura. It works fine on my hardware (Z390 Aorus Elite + i9 9700 + RX6600) although with the proper customization of kexts it can work well with Z390 boards and 9th gen CPUs. Although it is a beta version, it works very well without errors (at least in my case). Included recent versions of the kexts.
