67BGTEV,
At the present time, I have two groups of HP 8300 machines. The first group
has Nvidia GT730 graphics cards and i5-3470 CPU, and they are configured
as iMac13,2 with macOS Catalina 10.15.7 and OC 0.6.6. Here is a copy of the
EFI for this first group.
If you have a different CPU you need to replace the SSDT-CPU-PM-3470.aml
in ACPI and/or disable CPUFriend.kext, depending on how you generate the new
power management file.
If you are not using a Nvidia graphics card, you should remove the shikigva=256
boot argument. DRM in AppleTV works for me with the IGPU disabled in BIOS. If
you enable the IGPU in BIOS, it will default to headless AAPL,ig-platform-id of
07006201. If you want a connector-full IGPU for HD4000 graphics with i7-3770
or i5-3570K, you will have to add device properties for it.
You also have to add serial number, ROM, MLB, and UUID in Platform Info -> Generic
in the config.plist.
The second group of machines has AMD RX560 or RX 570 graphics cards and i5-3570K,
and they are configured as iMac15,1 with macOS Bis Sur 11.2 with OC 0.6.6. I'll clean
that EFI up and post it below. The EFI for this group is called EFI-AMD-3570K-BS.
Please back up your EFI before you consider using these and test them first on a USB
stick before installing them on your SSD or hard drive. No guarantees -- use at your own risk!