How to Fix Boot Stalls on ASUS B650 AM5 Motherboards During macOS Sequoia Installation

How to Resolve Early Boot Freezes on AMD AM5 Motherboards

Installing macOS Sequoia on the AMD AM5 platform (using an ASUS B650 PRIME motherboard) can be challenging. Many users experience freezes or instant reboots during early boot stages, even after following the basic instructions. This behaviour is usually caused by incorrect BIOS settings, missing AMD-specific ACPI tables, or outdated kernel patches in the OpenCore configuration.

1. Prerequisites

• Hardware Specs: AMD Ryzen 7000 CPU (e.g., Ryzen 5 7600), ASUS B650 PRIME motherboard, compatible AMD dGPU (like RX 6600, as AMD iGPU is unsupported).
• Required ACPI Tables: SSDT-CPUR (mandatory for AMD Zen 4/AM5 systems to map the processor correctly).
• Tools: ProperTree, MountEFI, and the latest release of OpenCore.

2. Compatibility Snapshot

• AM5 Support: Fully supported by OpenCore, but requires Zen 4 kernel patches.
• iGPU Limitation: Ryzen 7000 integrated graphics (Radeon 610M) are NOT supported in macOS. A compatible dedicated GPU (AMD Polaris, Vega, or Navi) is mandatory.

3. Installation Preparation

1. BIOS Settings: Navigate to the UEFI BIOS settings and configure the following:
   • Disable: Secure Boot, Fast Boot, CSM, and VT-d.
   • Enable: Above 4G Decoding, SVM (Virtualization), and XHCI Hand-off.
   • SATA Mode: Set to AHCI.
2. Installer Creation: Prepare a GUID partition style USB drive containing the macOS Sequoia installer.

4. EFI and config.plist Review

1. AMD Kernel Patches: Ensure that the Zen 4 kernel patches are added to your config.plist under Kernel -> Patch. You must update the core count patch to match your CPU cores.
2. SSDT-CPUR: Place SSDT-CPUR.aml in your EFI/OC/ACPI folder and add it to the ACPI list in config.plist.
3. Boot Arguments: Add -v keepsyms=1 debug=0x100 to view the verbose output during boot.

5. Post-Installation

1. USB Map: Generate a custom USB map to prevent sleep issues and unstable USB ports on your ASUS motherboard.
2. Mount EFI: Copy the final stable EFI from your USB drive to the SSD's EFI System Partition.

6. Troubleshooting

Reported Issue: Boot freezes during installer launch

1. Freeze at early boot: If it hangs before loading the kernel, ensure your BIOS firmware is updated to the latest version. Early AM5 BIOS builds had severe ACPI tables bugs.
2. Stuck on PCI configuration: Ensure Above 4G Decoding is enabled in the BIOS, and if the freeze persists, add npci=0x2000 to your boot-args.

7. Dual Boot and Advanced Configuration

• Dual Boot: Install Windows and macOS on separate physical NVMe SSDs to prevent OpenCore from injecting ACPI patches into Windows.

8. Verification, Maintenance and Rollback

• Verify installation: Ensure all USB ports work at their correct speed and that power management works correctly.
• Rollback plan: Keep a bootable USB drive with a verified working EFI folder before making any edits to the internal drive's ESP.

9. References and Glossary

• SSDT-CPUR: A custom ACPI table that resolves CPU mapping issues on AMD motherboards.
• AM5: AMD's latest socket architecture supporting Ryzen 7000 and newer CPUs.