System Specs

BIOS Settings

• Tweaker [TAB]
  • Extreme Memory Profile (XMP): Enabled (if supported by RAM)
  • Advanced CPU Settings
    • VT-d: Enabled
    • Intel Speed Shit: Enabled
• Settings [TAB]
  • Platform Power
    • Platform Power Management: Disabled
    • ErP: Enabled (so USB Power turns off, after PC is shut down)
  • IO Ports
    • Internal Graphics: enabled (if CPU has integrated graphics). NOTE: The config.plist uses dGPU for Display(s) and iGPU for computational tasks only by default. If you want to use the iGPU to drive a display you need a different Framebuffer Patch (see "EFI Install Instructions" for details).
    • OnBoard LAN Controller: Enabled
    • Audio Controller: Enabled (if On-Board Sound Card is used)
    • Above 4G Decoding: Enabled
    • Re-Size BAR Support: Disabled
    • IOAPIC 24-119 Entries: Enabled
    • Super IO Configuration
      • Serial Port: Disabled
    • USB Configuration
      • Legacy USB Support: Disabled
      • XHCI Hand-off: Enabled
    • Network Stack Configuration
      • Network Stack: Disabled
• Boot [TAB]
  • CFGLock: Disabled (only available on newer BIOS versions)
  • Windows 10 Features: Windows 10
  • CSM: Disabled (to get rid of legacy code from DSDT)

OpenCore Details

• System Definition: iMac20,2. SMBIOS data needs to be generated. I use OCAT for this.
• macOS Compatibility: 10.14 up to 12.4+ (10.14 requires iMac19,1 config)
• OpenCanopy: enabled
• Chime: no
• FileVault: Optional
• SIP: Disabled
• SecureBootModel: Disabled
• USB Ports Mapped: Yes, via ACPI. Details here

EFI Folder Structure

EFI
├── BOOT
│   └── BOOTx64.efi
└── OC
    ├── ACPI
    │   ├── DMAR.aml
    │   ├── SSDT-AWAC-ARTC.aml
    │   ├── SSDT-DMAC.aml
    │   ├── SSDT-EC-USBX.aml
    │   ├── SSDT-FWHD.aml
    │   ├── SSDT-PLUG.aml
    │   ├── SSDT-PMC.aml
    │   ├── SSDT-PORTS.aml
    │   ├── SSDT-RX580.aml
    │   ├── SSDT-SBUS-MCHC.aml
    │   └── SSDT-XSPI.aml
    ├── Drivers
    │   ├── HfsPlus.efi
    │   ├── OpenCanopy.efi
    │   └── OpenRuntime.efi
    ├── Kexts
    │   ├── AGPMInjector.kext
    │   ├── AppleALC.kext
    │   ├── CPUFriend.kext
    │   ├── CPUFriendDataProvider.kext
    │   ├── FeatureUnlock
    │   ├── Lilu.kext
    │   ├── NVMeFix.kext
    │   ├── RestrictEvents
    │   ├── SMCProcessor.kext
    │   ├── SMCSuperIO.kext
    │   ├── VirtualSMC.kext
    │   └── WhateverGreen.kext
    ├── OpenCore.efi
    ├── Resources (NOTE: removed files of sub-folders from tree view to reduce clutter)
    │   ├── Font
    │   ├── Image
    │   │   ├── Acidanthera
    │   │   │   ├── Chardonnay
    │   │   │   ├── GoldenGate
    │   │   │   └── Syrah
    │   │   ├── Blackosx
    │   │   │   └── BsxM1
    │   │   └── velickovicdj
    │   │  	└── EnterTwilight
    │   └── Label
    ├── config.plist
    └── config_iMac19,1.plist

About included ACPI Tables

My EFI Folder contains additional ACPI Tables besides the usual, which you won't find in the OpenCore Install Guide. Some of them are board-specific, some of them are modified versions of the regular tables, some are just cosmetic.

Here's what the extra tables do:

• DMAR: DMAR replacement table without Reserved Memory Regions so the I225-V LAN Card works in macOS Big Sur and Monterey.
• SSDT-AWAC-ARTC: Special variant of SSDT-AWAC. Disables AWAC Clock and enables RTC as ARTC instead. Also disables legacy HPET device.
• SSDT-PORTS: OS-agnostic USB Port Mapping Table for the Z490 Vision G. No additional USB Port kext or quirks are required. Since the USB ports are mapped via ACPI they will work in any macOS. See the "Additional Files" folder for a detailed list of available and mapped ports.
• SSDT-DMAC (optional): Adds a fake Direct Memory Access Controller to the device tree of I/O Registry. Disablked By default, since it's cosmetic.
• SDT-FWHD (optional): Adds fake Firmware Hub Device (FWHD) to I/O Registry. Used by almost every intel-based Mac. Disabled by default since it's comsetic.
• SSDT-PMC (optional): Adds fake Apple-exclusice PCMR Device to ACPI. Required for 300-series mainboards but optional on 400-series and newer. Disabled.
• SDT-RX580 (disabled) → Improves Metal Performance on Radeon RX580 cards. See the test results
• SSDT-XSPI (optional, enabled): Adds PCH SPI Controller to IORegistry as XSPI. So it's not a fake device but probably only a cosmetic change.

NOTE: More info about additional ACPI Tables can be found on my OC Little Repo

Disabled Kexts

The following Kexts are disabled by default since I don't know which CPU, GPU, Hard Disk and SMBIOS you will be using:

• AGPMInjector.kext → Injects Apple Graphics Power Management for the GPU into I/O Registry
• CPUFriend.kext and CPUFriendDataProvider.kext. Create your own DataProvider kext using CPUFriendFriend, replace the existing one and enable both
• NVMeFix.kext: recommended for all 3rd party NVMe SSD drives
• FeatureUnlock: see comments for details
• RestrictEvents: Only required when using MacPro7,1 SMBIOS. Needs revpatch=auto boot-arg to disable Warning about unpopulated RAM slots.

Installing macOS

Coming from Windows/Linux: If you are on Windows or Linux, follow the guide provided by Dortania. NOTE: No support from my end for issues related to UBS Installers created in Windows or Linux!

Coming from macOS: If you already have access to macOS, you can either download macOS from the App Store or use ANYmacOS instead. It's a hassle-free app than can download any macOS from High Sierra up to Monterey and create a USB Installer as well.

EFI Install Guide for OpenCore

1. Download latest OC EFI Release and unpack it
2. Select the config of your choice and rename it to config.plist
3. Open config.plist with OCAT and adjust the following parameters according to your hardware and software configuration:
   • Change csr-active-config based on the macOS version to disable SIP (when using GeForce Kepler Patcher, you have to disable SIP):
     
     
     • For Monterey: EF0F0000 (0xFEF)
       
     • For Big Sur: 67080000 (0x867)
     • For Mojave/Catalina: FF070000 (0x7FF)
     • For High Sierra: FF030000 (0x3FF)
       
       IMPORTANT: Using EF0F0000 also disables incremental system updates on macOS 11 and newer. So everytime an update is available, the full installer will be downloaded. To avoid this, either enable SIP temporarily from the OpenCore GUI or use 67080000 instead.
       
   • AMD GPUs may require additional boot-args. Check WhateverGreen's documentation for details.
   • If you want to use the Intel UHD 630 integrated graphics to drive a display, do the following in DeviceProperties > Add:
     • Disable PciRoot(0x0)/Pci(0x2,0x0)(put ## in front of it)
     • Enable #PciRoot(0x0)/Pci(0x2,0x0) (delete the #)
4. Getting the Intel(R) I225-V Ethernet Controller to work: read this
5. Generate SMBIOS data for iMac20,1 or iMac20,2.
6. Save the config.plist
7. Copy the EFI Folder to a FAT32 formatted USB Stick
8. Reboot from USB Stick
9. Perform an NVRAM Reset (hit Space Bar to reveal Tools)
10. Boot macOS
11. If your system boots successfully, mount your ESP and copy over the EFI Folder to you HDD/SSD and reboot.
12. Continue with Post-Install!

Strengthen Security (recommended)

Once you got macOS running, you may want to change the following settings to make your system more secure:

1. Enable System Integrity Protection (SIP): change csr-active-config to 00000000.
   NOTE: If you need GeForce Kepler Patcher, SIP needs to be disabled!

2. Under UEFI/APFS, change MinDate and MinVersion from -1 (disabled) to the correct values for the macOS version you are using. A list with the correct values for can be found here.
   

3. Change SecureBootModel from Disabled to j185f (for iMac20,2) or j185 (for iMac20,1). You should test these settings first booting from a USB flash drive since it can prevent the system from booting. Disable it for installing macOS Monterey if you have issues.

   IMPORTANT

   • Since SMBIOS iMac20,x is for an iMac with a T2 Security Chip, you won't be notfied about System Updates if SecureBootModel is set to Disabled. To workaround this, enable the following Kernel Patches in the config.plist:
     • Force IOGetVMMPresent
     • Reroute kern.hv_vmm_present patch (1)
     • Reroute kern.hv_vmm_present patch (2)
   • If you have to use Geforce Kepler Patcher to get your GeForce Kepler Card working, you have to set SecureBootModel to Disabled
   • SecureBootModel is only applicable to macOS Catalina and newer.

Optimizing CPU Power Management

You can follow my guide to use CPUFriendFriend to generate a CPUFriendDataProvider.kext alongside CPUFriend.kext to optimize the CPU Power Management for a more efficient performance. Have a look at the CPU behavior using Intel Power Gadget. The CPU idle frequency should be lower after adding the kexts:

Calculating Scan Policy (optional)

The items displayed in the Boot Picker Menu are based on a combination of bits representing supported devices (SATA, NVME, USB, etc.) and file systems (APFS, HFS, NTFS, etc.). There are 24 bits which can be turned on and off to modify what's displayed in the Boot Picker. The combination of selected bits create what's called the ScanPolicy. It's located under Misc > Security in the config.plist. The default value of my EFI is 0 (everything). Although this is great for compatibility, it will also display EFI Folders on drives which are not the boot drive as well.

To change the ScanPolicy to your liking, you can make use of this online calculator: https://oc-scanpolicy.vercel.app/. I am using 2687747 for example which hides EFI Folders and NTFS Drives. If I need windows I just boot it from the BIOS Boot Menu (F12).

IMPORTANT: Calculating a wrong ScanPolicy can lead to the Boot Picker being empty, so you can't boot into macOS. So make sure to test the value first by booting from FAT32 formatted USB Stick containing your EFI Folder with the new value for "Scan Policy".

Changing Themes

Besides the 3 themes from Acidanthera which provide the standard macOS look and feel, I've added 2 additional themes: BsxM1 (default) and EnterTwilight. To change them, do the following:

• Open config.plist
• Go to Misc > Boot and change PickerVariant to: Blackosx\BsxM1 or velickovicdj\EnterTwilight
• Save and reboot

To revert these changes, enter Acidanthera\GoldenGate as PickerVariant and change the Flavour of the NVRAM Reset Tool back to Auto.

NOTE: For more config tips and tricks, you can check out this.

Bootloader Chooser

I recently discovered BootloaderChooser which lets you pick the bootloader of choice prior to booting. This is how the folder structure looks like:

Basically, you put the "Clover" Folder on the same level as the the "OC" Folder and then replace the "BootX64.efi" in the "BOOT" Folder with the one that come with the Bootloader Chooser. Then you can select which Bootloader you want to use. Pretty nice for setting up your USB flash drive having Clover and OC to chose from:

Patching-in Kepler Drivers

Apple removed Keppler support from macOS Monterey beta 7. So users of NVIDIA GeForce Cards from the Kepler family need to patch them back in post-install using Geforce-Kepler-Patcher. If you require this patch, you can no longer boot with SIP enabled, so you have to disable it!