Enable undervolting on your Dell XPS 9500/9700 (or others)

[Custom90gt]

Figure reposting this one may be worth while.

Dell's lack of undervolting on their recent XPS systems is super annoying but thankfully on their 10th Gen stuff there is a way around it. I've tested this on my 9500 and 9700 and it worked like a champ. It does NOT work on 11th gen CPUs, I've tried it on my 9310 2-in-1 but Intel has blocked it.

This quick tutorial is something you use at your own risk. Neither myself or NBR is responsible if you mess something up, it doesn't work for you, or anything else happens. I cannot take full credit for this, I found this page which helped me tremendously.

It has been suggested that these variables can change with different bioses, and that's possible. It's also possible that Dell with enable undervolting on their own, but not likely. Having said that these flags have been tested and are working on:
Dell XPS 9700 Bioses: 1.04, 1.06, 1.32, 1.5.0, 1.6.3, 1.8.2, 1.9.2
Dell XPS 9500 Bioses: 1.4.0, 1.6.1, 1.7.1, 1.8.1, 1.9.1

I will update my Dell XPS 9500 to ensure support but sadly I no longer have a 9700 to test on.

If you don't have one of the bioses above or you want to upgrade your bios and it hasn't been tested please view the guide found here.

Click the spoiler below to learn how to enable undervolting on your XPS 9500/9700.

Create a EFI USB Boot Drive

1. Download the grubx64.efi file from v1.0 alpha release available here.
2. Get (or format) a blank FAT32 flash drive.
3. Create a folder called EFI. Within this EFI folder, create a folder called Boot.
4. Place the grubx64.efi folder above into the EFI/Boot folder path.
5. Rename grubx64.efi to bootx64.efi.

You should now have a flash drive with one file, bootx64.efi, located in the path X:/EFI/Boot (where X is your flash drive’s drive letter.) Time to boot it!

Disable Secure Boot in BIOS and Boot Prepared EFI USB Drive
Before your computer can boot the EFI flash drive, you will have to disable the Secure Boot option in your BIOS. To do so simply go into the bios with F2 and under the boot options there should be a Secure Boot mode, set that to disable. After that leave your USB drive in and hit F12 to select your USB drive to boot from.

Edit EFI Variables of Interest (again after verifying they are the CORRECT variables):
Once in the EFI shell simply type (without the quotations):
"setup_var CpuSetup 0xDA 0x0"
"setup_var CpuSetup 0x3E 0x0"
Once you change the variables, you can simply unplug your flash drive, reboot, re-enable SecureBoot, and boot back into Windows.

Now you can actually use throttle stop to undervolt!

 

If you have a XPS 9510/9710/Precision 5560:

"setup_var CpuSetup 0xDF 0x0"
"setup_var CpuSetup 0x43 0x0"

 

[Aaron44126]

Also working with Precision 7560 (confirmed by @Ionising_Radiation).  It will probably work with most Dell systems with the undervolt block.

https://www.nbrchive.net/forum.notebookreview.com/threads/precision-7560-7760-owners-thread.836381/page-80.html#post-11114871 — Points back to the same guide that you have here.

(Apologies for broken images, haven't gotten to cleaning up attachments in the archive yet.)