G635 BIOS 318 – Can’t Enter BIOS in dGPU Mode, Downgrade Fails

[JamXi]

I updated my G635 to BIOS version 318. Since then, I can’t enter BIOS in dGPU mode—there’s no boot screen, no sound, and it just goes straight into Windows.

Also, I can’t open the boot menu during startup, and trying to enter UEFI settings from Windows (Advanced Startup) results in a black screen.

However, everything works fine in iGPU (MSHybrid) mode—BIOS access and boot menu are normal.

I tried downgrading to BIOS 315 or 313 using EZ Flash, but it always says “BIOS update failed.”

Is there any way to downgrade or fix this dGPU BIOS issue?

[BTX_EBRO]

I had the same problem in G815LR (Asus ROG Strix G18) [BIOS ver. 318 too].
In my case I was trying solutions from asus.com and internet - NOTHING ....
I removed SSD, and run without ssd. Laptop automatically goes to BIOS setup. I've changed from dGPU ONLY to dynamic. Put SSD to laptop, and now, all is OK.

[zygote_rog]

Same problem here. ASUS ROG Strix Scar 16 — brand new. Updated to the latest BIOS (G635LX.318). With dGPU-only enabled (Ultimate mode) , I can no longer access the BIOS. It boots straight into Windows without even showing the boot spinner.

[carathorys]

I’m experiencing a similar issue since updating to version 318, which was a mandatory update from Windows Update. Additionally, when using dGPU-only mode, the system applies 200% DPI instead of the expected 150%, and screen brightness adjustments don't work at all.

If I switch back to shared GPU mode, I can enter the BIOS, the screen brightness works properly, but performance takes a hit.

I’ve also noticed that if I remove my Gen 5 SSD, the system works as expected in dGPU-only mode. This leads me to believe the issue might be related to PCIe Gen 5.