iGPU option not available in BIOS when the Legacy Boot Mode enabled

[vortex1]

First of all, my iGPU was originally showing in BIOS and Windows Device Manager no problem.

I later realised I couldn't get into the BIOS normally (ie. with the DEL key on startup) without having to shut the PC down, then clearing CMOS first, then restarting the PC.

I realized it had something to do with the Boot configuration in the BIOS, and I know I have to have the Asus splash screen display on boot up.  So I went into the BIOS and disabled Fast Boot; Then checked Secure Boot and kept OS Type as Windows UEFI Mode; then I set CSM (Compatibility Support Module) to Enabled or to 'Launch'.

Now the Asus splash screen appears on boot and I can keep pressing DEL and I can get into the BIOS as normal.

However - Now my iGPU is not available as a option (to enable in the BIOS), and therefore (obviously) not appearing in Device Manager in WIndows.

I want to have both options on - iGPU ON and Legacy Boot ON.

Does anyone know how I can fix this?

Btw, I had this problem with a previous CPU & Motherboard that I thought were faulty and I've just replaced to what I have now - so it's not my hardware. Also, my BIOS has been updated to the latest version.

Also: See my reply post below for more info ⬇

EDIT: I re-checked and I've found I can only boot into Windows if I have CSM on, otherwise I get a hanging black screen. Also if I have CSM on - I can boot into BIOS, however iGPU is inaccessible!

[vortex1]

This Reddit post appears to show others with the same issue, and there didn't appear to be a fix (With CSM Enabled, i don't see the iGPU inside the "System Agent (SA) Configuration)" :

https://www.reddit.com/r/iBUYPOWER/comments/my2yvy/no_igpu_option_in_asus_uefi_bios_please_help/

[JohnAb]

Did you update the BIOS? I just had very similar problems where I couldn't get into the BIOS at all after a 3802 update, I could only get there after a total power off, otherwise just a blank screen. Now I've gone back to 3701 and everything is working again. I can't comment on your iGPU issues. 

[vortex1]

Yes I updated the BIOS to the latest version - this problem has occurred on the newest BIOS and the previous version.

The problem is that now I have 'enabled' Legacy Boot via enabling CSM - the iGPU configuration setting has disappeared from the BIOS.

And if I 'disable' Legacy Boot it will reappear - and I'd like to turn both settings on, not one or the other.

[FixItWorse]

iGPU and CSM are simply not compatible, that's why it disappears. Just as many other "newer" things and CSM are not compatible.

Normal behavior.

[vortex1]

Yep. I now realize that I can't have iGPU ON and Legacy Boot ON.

I am going through a process of rebuilding my pc including replacing the boot drive and RAM, so hopefully I will be able to have a normal UEFI bios again and be able to turn my iGPU on. I really didn't want to have CSM on, but at the time was the only way I could boot, so there was clearly a serious fault with the system.

[FixItWorse]

Feel free to mark your question as solved, and If you ever wish to DM me with a specific question, feel free.

[vortex1]

Thanks for the invite - I will DM you once I receive my new m/board and set everything all back up and try to re-install Windows - which I was also unable to do with my old components (boot SSD & m/board) - see my other thread: https://rog-forum.asus.com/t5/intel-700-600-series/can-t-install-windows-get-a-black-screen-when-pc-...

As far as marking this thread as solved - it actually isn't because until I set my new system up, I am unsure if I will still have this iGPU issue with a UEFI BIOS - which is exactly why I was messing about with CSM - when I would have rather not. I wanted UEFI ON and iGPU ON.

[FixItWorse]

Certainly, look forward to your reply.

[achugh]

Hi @vortex1 I believe you will be able to turn OFF CSM the moment you replace your GFX Card. Since I know about your other post as well, I recommend that when you start building your system again, keep your CSM OFF and slowly plugin everything. My guess is that the moment you are going to install your MSI RTX 4070 is when you will have an issue and it will more than likely force you to enable CSM again.

The only thing I have seen as an option that worked for someone is to go into your SA Configuration and set your PEG SLOT to run at GEN4 instead of GEN5 you see below for my build. On an MSI GFX Card, it MAY allow you to post with CSM DISABLED.

My understanding is that the ASUS BIOS and MSI RTX Cards are not able to negotiate the PCIe speed properly during boot without CSM enabled. So manually setting the speed gets over this hurdle and things move forward.

SA Configuration\PCI Express Configuration

NOTE: Just because setting the speed as a workaround worked for something does not mean it will work for you and others. It is just a pure guess at this time. I hope this helps you and others as this trick does work in few use cases.