r/LenovoLegion • u/Significant-Pack-317 • 5d ago

Support Need help enabling IOMMU on Legion 5 15ARH05

Hi everyone,

I’m looking for some help with enabling IOMMU on my Lenovo Legion 5 15ARH05 (82B5).
My goal is to play Fortnite tournaments. Fortnite/Epic is requiring IOMMU for the competitive functionality I’m trying to use, but I can’t find an IOMMU option anywhere in my BIOS.

My specs/configuration:
Laptop: Lenovo Legion 5 15ARH05
CPU: AMD Ryzen 5 4600H
BIOS: EUCN41WW (updated from EUCN29WW)
BIOS mode: UEFI
Windows: Windows 11 Home
AMD SVM Technology: Enabled
AMD Platform Security Processor: Enabled
Secure Boot: Enabled
Kernel DMA Protection: Off

I’ve checked all the available BIOS menus, but there is no visible IOMMU/AMD-Vi option.

I found this thread specifically for the 15ARH05:
https://winraid.level1techs.com/t/howto-enable-hidden-features-of-lenovo-legion-5-15arh05/35995/5

It appears that IOMMU and DMAR can be enabled using hidden AmdSetup variables:

setup_var_cv AmdSetup 0xCA 0x1 0x1
setup_var_cv AmdSetup 0xCD 0x1 0x1

However, I’m not comfortable doing this blindly, because I really need to make sure the laptop will still boot normally afterwards. I don’t want to brick the laptop or end up with a system that won’t POST/boot.
I’ve also seen people mention that IOMMU may already work without a visible BIOS option, especially on Legion 5 models, so I’m not sure whether modifying these variables is actually necessary.

Could someone familiar with the Legion 5 15ARH05 / AMD BIOS help me determine the safest way to enable or verify IOMMU?

Fyi: I am not really smart regarding codes and technical stuff.

2 Upvotes

100% Upvoted

5 comments sorted by

1

u/AutoModerator 5d ago

For real-time discussion and access to our full guide library join the Discord: https://discord.gg/legionseries

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

1

u/q123459 4d ago

you can ask lenovo support for firmware with this option unlocked

1

u/AtlasLucario 4d ago

there is a way to enable the hidden advanced settings in the bios, grab this: https://github.com/Thomashighbaugh/Lenovo-Legion-Advanced-Bios

and be careful about what you toggle in the advanced sections, only toggle what you need to toggle

1

u/Significant-Pack-317 3d ago

Is this safe since I updated the BIOS?

1

u/AtlasLucario 3d ago

yes, i used it to disable intel dynamic tuning technology since its got a bug with it in quiet mode