[Problem] AMD IOMMU with Lenovo Legion 5 15ARH05

BIOS/UEFI Modding BIOS Modding Guides and Problems
1

Hi everyone,

I have a Lenovo Legion 5 15ARH05 (machine type 82B5) with the following specifications:

  • Laptop: Lenovo Legion 5 15ARH05

  • CPU: AMD Ryzen 5 4600H

  • Current BIOS: EUCN41WW (February 2024)

  • Operating system: Windows 11 Home

  • BIOS mode: UEFI

I need to enable AMD IOMMU to meet the requirements for Fortnite competitive tournaments.

Here is what I have checked so far:

  • AMD SVM Technology is enabled in the BIOS.

  • AMD Platform Security Processor is enabled.

  • Secure Boot is enabled.

  • I cannot find an IOMMU option anywhere in the BIOS setup.

  • Windows reports Kernel DMA Protection as Off.

I found this older thread that describes enabling IOMMU and DMAR on this exact laptop model using setup_var_cv commands:

https://winraid.level1techs.com/t/howto-enable-hidden-features-of-lenovo-legion-5-15arh05/35995/5

However, I am currently running BIOS EUCN41WW, and I have not found confirmation that these commands work correctly with this version. I have also seen reports that IOMMU may revert to Auto after reboot on some BIOS versions.

I also found this Advanced BIOS project, which lists the Legion 5 15ARH05, but I could not confirm whether it supports EUCN41WW:

https://github.com/Thomashighbaugh/Lenovo-Legion-Advanced-Bios

My questions are:

  1. Has anyone successfully enabled IOMMU on the Legion 5 15ARH05 with BIOS EUCN41WW?

  2. Are the setup_var_cv offsets in the older Win-Raid guide still valid for this BIOS version?

  3. Is there a way to enable IOMMU permanently without downgrading the BIOS or risking a failed boot?

  4. Has anyone successfully used the Advanced BIOS/SREP method on this exact model and BIOS version?

  5. Is there a reliable way to verify that IOMMU is actually enabled in Windows after making the change?

I have a USB flash drive available, and I am willing to follow a carefully explained procedure. However, I want to avoid unnecessary BIOS modifications because I need the laptop to remain bootable and keep my existing Windows installation and files intact.

I would greatly appreciate any advice from someone who has tested this on the same laptop and BIOS version.

FYI: I am noob when it comes to this kind of specific technicall stuff.


Edit by Fernando: Thread title customized