Adjust BIOS settings¶
Most of these options will not all be present in your firmware. Match them as closely as you can, and do not worry about the ones that are missing.
Reset your BIOS to its defaults before you start.
Disable
- Fast Boot
- Secure Boot
- Serial/COM Port
- Parallel Port
- Compatibility Support Module (CSM)
- Thunderbolt
- Intel SGX
- Intel Platform Trust
- CFG Lock (MSR 0xE2 write protection)
Enable
- VT-x
- Above 4G decoding
- Hyper-Threading
- Execute Disable Bit
- EHCI/XHCI Hand-off
- OS type: Windows 8.1/10 UEFI Mode — some boards need Other OS instead
- DVMT Pre-Allocated (iGPU memory): 64MB or higher
- SATA Mode: AHCI
CFG Lock must be off
Your machine will not boot with CFG-Lock enabled. If the option is not
in your firmware at all, enable AppleXcpmCfgLock under
Kernel → Quirks in the config instead.
CSM
Must be off in most cases. GPU errors and stalls like gIO are common
when it is enabled.
Thunderbolt
Off for the initial install. Thunderbolt causes problems if it is not set up correctly, and setting it up is a job for after macOS runs.
Disable
- Fast Boot
- Secure Boot
- Serial/COM Port
- Parallel Port
- Compatibility Support Module (CSM)
- IOMMU
Enable
- Above 4G Decoding
- EHCI/XHCI Hand-off
- OS type: Windows 8.1/10 UEFI Mode — some boards need Other OS instead
- SATA Mode: AHCI
Above 4G Decoding must be on
If you cannot find the option, add npci=0x3000 to boot-args instead.
Do not have both enabled at the same time.
On Gigabyte/Aorus and ASRock boards, enabling it may break drivers such
as Ethernet, or stop other operating systems booting. If that happens,
turn it off and use npci instead.
Resizable BAR, on 2020 and newer firmware
Enabling Above4G may make Resizable BAR Support available on some
X570 and newer boards. If it is enabled, set
Booter → Quirks → ResizeAppleGpuBars to 0.
Threadripper 3990X
macOS panics above 64 threads in the kernel. The 3990X has 128, so half of them have to go — disable hyper-threading in the BIOS.