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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/lzhoang2801/OpCore-Simplify/llms.txt

Use this file to discover all available pages before exploring further.

Before you copy your freshly built EFI to a USB drive and boot into OpenCore, your system’s firmware must be configured correctly. OpenCore relies on specific BIOS and UEFI settings to load macOS, and an incompatible firmware configuration is one of the most common reasons a Hackintosh fails to boot at all. Taking a few minutes to verify these settings now prevents hours of troubleshooting later.

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How OpCore Simplify Checks Your Firmware

At the end of every EFI build, OpCore Simplify runs the check_bios_requirements() function against your hardware report. This function compares what your firmware currently reports — firmware type, Secure Boot status, and GPU Resizable BAR state — against what OpenCore needs. Any setting that is out of place is printed as a numbered action item in the Before Using EFI screen before the Results folder is opened.
The BIOS requirements check is based on the hardware report generated at build time. If you change your BIOS settings and rebuild, the list will update accordingly.

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Required Settings

The following settings are the ones OpCore Simplify may flag as required. Check each one in your BIOS before attempting to boot.

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1. Enable UEFI Mode (Disable Legacy/CSM)

OpenCore is a UEFI-native bootloader and cannot run in Legacy/BIOS mode. If your hardware report recorded a Legacy firmware type at the time of scanning, the tool will instruct you to disable the Compatibility Support Module (CSM) and switch to pure UEFI mode.
  • Look for options labelled CSM, Compatibility Support Module, Legacy Boot, or Boot Mode in your BIOS.
  • Set the boot mode to UEFI Only and disable CSM entirely.
  • After disabling CSM, your BIOS boot order may reset — re-add your USB drive or target disk as a UEFI boot entry.

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2. Disable Secure Boot

macOS and the OpenCore bootloader are not signed with a Microsoft-trusted certificate. When Secure Boot is active, your firmware will refuse to launch any unsigned EFI binary, which prevents OpenCore from loading.
  • Find Secure Boot under the Security or Boot tab of your BIOS.
  • Set it to Disabled.
  • On some boards you may also need to clear any enrolled keys or set the Secure Boot mode to Setup Mode first.

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3. Enable Above 4G Decoding (Modern Intel Desktop Chipsets)

For Intel desktop platforms using chipsets from Comet Lake and newer — the Comet Lake platform is the first entry at index 112 of OpCore Simplify’s internal chipset table, and this requirement applies to all chipsets listed from that point onwards — the system must be able to address PCIe device memory above the 4 GB boundary. Without this, certain GPUs and NVMe controllers may fail to initialise under macOS. The tool flags this requirement when all three of the following are true:
  • The platform is a desktop (not a laptop).
  • The chipset belongs to the Comet Lake platform or any newer Intel platform (Rocket Lake, Alder Lake, Raptor Lake, Meteor Lake, Lunar Lake, Arrow Lake, and so on).
  • No GPU in the system has Resizable BAR enabled.
To address this:
  • Find Above 4G Decoding (sometimes labelled Above 4G Memory/PCI Decoding or Large BAR support) in your BIOS under the Advanced or PCI/PCIe section.
  • Set it to Enabled.

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4. Disable Resizable BAR / Smart Access Memory

Resizable BAR (ReBAR) and AMD’s marketing name for the same feature, Smart Access Memory (SAM), allow the CPU to access the entire GPU frame buffer in a single BAR window. When Above 4G Decoding is required but Resizable BAR is not active, OpCore Simplify pairs the Above 4G Decoding requirement with an explicit instruction to ensure Resizable BAR is set to Disabled. This matters because enabling Above 4G Decoding while Resizable BAR is partially or incorrectly configured can cause hangs during PCIe enumeration in macOS.
  • Find Resizable BAR, Re-Size BAR Support, or Smart Access Memory in your BIOS.
  • Set it to Disabled unless OpCore Simplify has specifically generated a ResizeAppleGpuBars device property for your GPU.
OpCore Simplify automatically configures ResizeAppleGpuBars in your config.plist based on the Resizable BAR information in your hardware report. If your GPU had Resizable BAR enabled at scan time, the tool may have set this property to 0 to keep macOS stable — do not change it manually without understanding the implication.
The following settings are not enforced by OpCore Simplify’s automatic check, but are widely recommended by the Hackintosh community for stability and compatibility. Review each one and apply where possible.
SettingRecommended ValueWhy
Fast BootDisabledSkips full hardware initialisation, which can prevent OpenCore from being detected
CFG Lock (MSR 0xE2 write protection)DisabledRequired for proper CPU power management; if unavailable, set AppleXcpmCfgLock quirk in config.plist
SATA ModeAHCImacOS does not support Intel RST/RAID SATA modes
VT-d (Intel Virtualization for Directed I/O)DisabledCan cause IOKit conflicts; if unavailable, set DisableIoMapper quirk in config.plist
Intel Platform Trust Technology (PTT) / AMD fTPMDisabledCan cause random stalls and slow boots on some boards
Intel SGXDisabledNot used by macOS and can interfere with memory map
Wake on LAN / Wake on USBDisabledPrevents unexpected wake events in macOS
If you cannot find the CFG Lock option in your BIOS, you can work around it by enabling the AppleXcpmCfgLock quirk under Kernel → Quirks in your config.plist. This is already handled automatically by OpCore Simplify for most configurations.

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Manufacturer Name Variations

BIOS menus differ significantly between motherboard manufacturers (ASUS, Gigabyte, MSI, ASRock, etc.) and even between firmware revisions on the same board. The setting names listed above are generic descriptions — your board may use a different label.
Always consult your motherboard’s manual or the manufacturer’s official support site when you cannot locate a specific option. Searching for your board model alongside the setting name (e.g., “ASUS ROG Z790 disable CSM”) usually surfaces community guides with screenshots.
Skipping the BIOS configuration steps outlined above will very likely result in an immediate boot failure, a black screen, or system instability. OpenCore is strict about the firmware environment it expects. Complete every flagged requirement before your first boot attempt.

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Next Steps

Once your BIOS is configured, proceed to USB port mapping before installing macOS.

USB Mapping

Replace the placeholder UTBDefault.kext with your own custom USB map

Building Your EFI

Review what OpCore Simplify built for you

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