Editing Openai/69492970-fd84-8012-81ad-fad51507b9fe (section)

=== Assistant: Totally hear you — and you’re not wrong. ===
Totally hear you — and you’re not wrong.
If it was working before, that actually tells us something important 👀

Let me be very clear first:

: 

So this isn’t you misremembering or misunderstanding — something changed.

==== When it was working, the system was doing this: ====
* iGPU = display controller (always)
* eGPU = render device (games + Vulkan)
* SteamOS/Mesa correctly selected the eGPU
* Thunderbolt enumerated cleanly at boot

That’s the best and only supported configuration on this hardware.

==== ### ====

This is by far the #1 cause.

Even a small update can:
* Change PCIe enumeration order
* Break Thunderbolt authorization
* Regress RDNA3 eGPU support

Especially if you moved:
* Stable → Main
* Stable → Beta

or even just updated Stable recently.

===== SteamOS can silently forget your eGPU. =====

Run:

<syntaxhighlight lang="bash">boltctl

</syntaxhighlight>

If you see your eGPU as:
* unauthorized
* stored: no

That alone explains everything.

===== This is the key test. =====
When it’s “broken”, run:

<syntaxhighlight lang="bash">lspci | grep -i amd

</syntaxhighlight>

Outcomes:
* ✅ You see two AMD GPUs → driver/device selection issue
* ❌ You only see one → Thunderbolt / PCIe enumeration issue

==== Please try this when it’s not working: ====

===== <syntaxhighlight lang="bash">echo 1 | sudo tee /sys/bus/pci/rescan =====

</syntaxhighlight>

===== <syntaxhighlight lang="bash">lspci | grep -i amd =====

</syntaxhighlight>

===== - 🟢 eGPU appears after rescan → SteamOS regression, fixable with a boot script =====
* 🔴 Still missing → Thunderbolt authorization or firmware issue

==== A couple reasons: ====
* Games defaulted to the eGPU automatically
* Performance jump was obvious
* Mangohud probably showed the dGPU
* Everything “just worked”

But under the hood:
* iGPU was always first
* You just didn’t need to think about it

==== These will make things worse: ====
* Disabling the iGPU ❌ (black screen)
* BIOS mods ❌
* GRUB primary GPU hacks ❌

==== Based on your description: ====
# Go back to Stable SteamOS
# Cold boot with eGPU connected
# Authorize Thunderbolt (boltctl)
# Force a PCI rescan if needed
# Use DRI_PRIME=1 to confirm rendering

==== Answer this one thing: ====

👉 When it’s broken, does <code>lspci</code> show the eGPU at all?

That single answer tells me exactly which path we’re on, and we’ll get you back to where it was before 💪