[Guide] How to Undervolt 8th-11th gen Intel Laptops

[thekingofmonks]

Undervolting 8th-11th gen Intel Laptops

 

Intel has at one point disabled undervolting features in newer bioses for Coffee Lake (8-9th gen) and newer mobile CPUs due to a security flaw. Reverting to an older bios does not get the features back.
Here's how to do it:

 

[Disclaimer]

- Do this at your own risk, I am not responsible for any mistake you might make. Follow the steps carefully.

- This method is not permanent. The values that enable undervolting may be reset following a bios reset, a bios flash or random firmware updates.

 

 

Prequisites

All of the following are easy to find:

• Universal bios backup toolkit
• UefiTool
• IRFExtractor
• Notepad++ (for opening very large text files)
• grubx64.efi (NOT bootx64.efi)

Identifying the overlocking lock vars:

1. Obtain your device's bios from the official site. Otherwise, use 'Universal bios backup toolkit' to save the bios while making sure that the backup ROM size corresponds to that of your bios chip.
2. Open the bios in uefitool. Search for 'overclocking lock'. Extract this var's root, which is called 'Setup' (for Coffee Lake) or 'CpuSetup' (for Comet/Tiger Lake) into a .ffs file.
3. Convert the .ffs file into a .txt file with IRFExtractor.
4. Open the .txt file with a text editor (preferably notepad++).
5. Search for 'CFG Lock' and 'Overclocking Lock' and identify each var's value. Make sure that they are set to 0x1 (= locks are enabled by default)

Example with my Asus G531GT :

CFG Lock, VarStoreInfo (VarOffset/VarName): 0x6F0, VarStore: 0x1
Overclocking Lock, VarStoreInfo (VarOffset/VarName): 0x78C, VarStore: 0x1

(here for instance, the CFG Lock is 0x6F0 and the Overclocking Lock is 0x78C)

Creating a bootable Grub usb and modifying the lock vars:

1. Use a FAT32 flash drive and create the following directory: [Drive letter:]/EFI/Boot
2. Paste the 'grubx64.efi' into the directory and rename it to 'bootx64.efi' so it gets recognized at boot
3. Restart your laptop and disable secure boot in the bios
4. Boot into the flash drive from the boot menu
5. Once Grub has loaded, type and enter the following commands without quotation marks:

• "setup_var Setup <your CFG Lock var value here> 0x0"
• "setup_var Setup <your Overclocking Lock var value here> 0x0"

(Replace 'Setup' with 'CpuSetup' if you have a Comet/Tiger Lake CPU)

 

The console should respond to each command with the following:
successfully opened Setup/CpuSetup
Offset <var value> is 0x0
Writing 0x00 to offset <var value>

 

All done
And don't forget to re-enable secure boot in the bios afterwards

Edited July 10, 2023 by thekingofmonks
Some clarifications

[Somerandomtechyboi]

34 minutes ago, thekingofmonks said:

.ffs file

Wonder why they had to use that file type that just so happens to be an abbreviation of a phrase that you say when you are very frustrated

[liwahadri]

It's still locked for me. I've tried changing values and it tells me "successful change 0x0" after a reboot, but the issue persists. I've also checked the throttlecpu options and they're still disabled, that wasn't the solution.

 

CPU: i5 1135g7 gen11, Huawei Matebook D15