I can't install Linux on the ASUS ExpertBook B9450FA (BIOS 319): I can't switch from Intel RST to AHCI even though I've modified the EFI PchSetup variable. I need help

Hello, I tried installing Mint on my Asus B9450FA laptop (BIOS 319). I followed the instructions from Claude and Deepseek, but we weren't able to switch to RST. Additionally, I confirmed that BIOS v319 doesn't offer the option to switch to AHCI and that the vmd module isn't compatible with this hardware. I’m specifically looking for other users of the same model who have successfully installed Linux natively to learn their method.

Thanks in advance for your help.

Hardware:



Laptop: ASUS ExpertBook B9450FA

BIOS: version 319 (InsydeH2O) – latest available

CPU: Intel Core i7-10510U (Ice Lake)

Storage: 1 TB NVMe SSD (internal) – Windows 11 installed

Goal: Install Linux Mint 22.3 in dual boot (NVMe invisible under RST)

https://www.asus.com/us/laptops/for-work/expertbook/asus-expertbook-b9-b9450/techspec/



Problem in short:

The BIOS does not expose an option to switch SATA mode from Intel RST (RAID) to AHCI. Without AHCI, Linux cannot detect the internal NVMe drive. We have tried to modify the UEFI variable PchSetup directly, but the change does not persist – the firmware reverts it on every reboot.



What we did (detailed):

Preparation:

BitLocker fully decrypted on all partitions.

Fast Boot disabled in BIOS.

Secure Boot enabled (did not block UEFI Shell access).

storahci driver prepared in Windows registry (Start = 0x0).



Identified the correct byte:

Dumped PchSetup from /sys/firmware/efi/efivars/ in Linux Mint live.

The RAID/AHCI control byte is at offset 0x08 in the efivars dump (9th byte of the first line).

In the pch.bin file exported by dmpstore, the equivalent offset is 0x32 (due to a 0x30-byte EFI header).

Current value = 0x03 (RAID), target = 0x00 (AHCI).

No checksum or interdependency found in the full dump.



Attempted modification:

Used dmpstore in UEFI Shell (Ventoy USB) to export PchSetup to pch.bin.

Edited pch.bin with PowerShell (also tried HxD) – changed byte at offset 0x32 from 0x03 to 0x00.

Used a second script (startup2.nsh) to re-import the modified pch.bin into NVRAM (dmpstore -l).

Verified after reboot: the byte in efivars is still 0x03 – the change did not persist.



What we ruled out:

No hidden SATA mode option in BIOS (confirmed by ASUS support docs and binary analysis).

No vmd module needed (Ice Lake does not use Intel VMD; that is for Tiger Lake+).

No obvious checksum or write protection error message – dmpstore -l succeeded without errors, but the firmware silently overrides the value.



Collaboration:

Two AI assistants (DeepSeek and Claude) worked together on this. DeepSeek guided the step-by-step procedure, Claude acted as quality control and cross‑checked each technical decision. Both confirmed that the firmware actively rejects writes to this variable – likely a deliberate lock by ASUS.



Current status:

Windows 11 still works normally (RST mode).

Linux Mint live still cannot see the NVMe.

No data loss or hardware damage.

Questions for the community:



Has anyone successfully switched an ASUS ExpertBook B9450FA (or similar InsydeH2O laptop) from RST to AHCI? If so, how?

Is there any known hidden EFI variable or alternative method (e.g., setup_var, ru.efi, or a specific BIOS key combination) that works on this model?

Could a BIOS mod (like unlocking hidden menus) be a feasible last resort?



Thank you very much in advance. Any insight is appreciated.

https://redd.it/1tk1a3n
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