[Request] Unlock iGPU "Aperture Size" on Gigabyte C246M-WU4

Hi all,

I’m new to this forum.

I have a Gigabyte C246M-WU4 motherboard and I’m trying to enable the selection of the iGPU Aperture Size in the BIOS but I don’t know where to start as I’ve never modified a BIOS before.

The option isn’t available in the BIOS and it isn’t mentioned in the manual.
However, if I open the latest BIOS file in AMIBCP, I can see that the option is there:

I don’t know why AMIBCP reports “Show = Yes” for this parameter because it clearly isn’t there in the BIOS.

The latest BIOS can be downloaded from here:

Would you be able to help me with this?


What you see with AMIBCP is the code only, default NVRAM variables has his settings, modern AMI V bios changes made with AMIBCP usually doesn’t work as other modules need changes, this utility was and is valid for AMI IV core bios.
You may need to edit AMIsetup and AMISetupdata and so on… look in the forum.

Thanks @MeatWar for the reply.

After I posted the message, I looked through the various forum posts.
So far what I did was:

  1. Extracted the Setup module from the BIOS file with UEFI tool
  2. Converted the Setup module with ifrextract
  3. I have verified that Aperture Size is present and looks like this:
0x45380 		One Of: Aperture Size, VarStoreInfo (VarOffset/VarName): 0x831, VarStore: 0x1, QuestionId: 0x5B1, Size: 1, Min: 0x0, Max 0xF, Step: 0x0 {05 91 38 0D 39 0D B1 05 01 00 31 08 14 10 00 0F 00}
0x45391 			One Of Option: 128MB, Value (8 bit): 0x0 {09 07 3A 0D 00 00 00}
0x45398 			One Of Option: 256MB, Value (8 bit): 0x1 (default) {09 07 3B 0D 30 00 01}
0x4539F 			One Of Option: 512MB, Value (8 bit): 0x3 {09 07 3C 0D 00 00 03}
0x453A6 			One Of Option: 1024MB, Value (8 bit): 0x7 {09 07 3D 0D 00 00 07}
0x453AD 			One Of Option: 2048MB, Value (8 bit): 0xF {09 07 3E 0D 00 00 0F}
0x453B4 		End One Of {29 02}
  1. VarStoreId: 0x1 is named “Setup”
0x32975 	VarStore: VarStoreId: 0x1 [EC87D643-EBA4-4BB5-A1E5-3F3E36B20DA9], Size: 0x16E0, Name: Setup {24 1C 43 D6 87 EC A4 EB B5 4B A1 E5 3F 3E 36 B2 0D A9 01 00 E0 16 53 65 74 75 70 00}

Do you confirm that if I want to change the Aperture Size from the default value of 256MB to 2048MB, all I have to do is boot into grub-mod-setup_var and execute the following command?:

setup_var_cv Setup 0x831 0x1 0xF

Does that persist a machine reboot?


No, they will never persist, until a dump to flash as it is, or mod/hex edited

Similar and not easy for inexperienced users, also its not always the same for all models/bios:
OverPowered TONGFANG CyberPower Machrevo MACHENIKE - Unlocked BIOS Guide W/ Files - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum (level1techs.com)

Is there a link or a guide that explains how to do it?

I read in other posts that modifying NVRAM settings is really tricky

Ok, nevermind. This is no longer necessary

I found this post that shows how to unhide a section of the bios to uncover the “aperture size” setting:

As I was following it and applying the same to my BIOS, something didn’t quite match because it appeared that aperture size for my BIOS was already visible…there was no “IF statement” to hide it.
Yet in the BIOS it wasn’t there.

It turned out that the entry has been unlocked by Gigabyte in one of the latest firmware updates and all I add to do was to clear the CMOS and it now shows correctly in the BIOS. (It still isn’t mentioned in the manual).

Thank you for you help.