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Intel-undervolt: CPU undervolting and throttling configuration tool for Linux

(github.com)
132 points cl3misch | 14 comments | 17 Jun 24 22:44 UTC | HN request time: 0.783s | source | bottom
1. chx ◴[18 Jun 24 01:44 UTC] No.40713262[source]▶
> my i7-8650U

those can but 10nm CPUs after Plundervolt can't undervolt , it's disabled from UEFI and not only there's no option to reenable it in the UI, the very EFI variable itself is write locked. I have an X1 Gen 4 (Intel 11th gen) and you just can't do it.

replies(4): >>40713587 #>>40714466 #>>40715686 #>>40718273 #
2. lm411 ◴[18 Jun 24 02:44 UTC] No.40713587[source]▶
Damn, you mean we can't just swap resistors to under/over volt anymore?

I am getting old.

(tongue in cheek, and yes, I am getting old)

Shit, I remember just using a pencil to lower resistance values.

replies(2): >>40713686 #>>40714469 #
3. ngneer ◴[18 Jun 24 03:03 UTC] No.40713686[source]▶
You can. The main thing is that software-based attacks are easier to perform.
replies(1): >>40713750 #
4. chx ◴[18 Jun 24 03:14 UTC] No.40713750{3}[source]▶
That'd be reason to take away the reenable from UEFI but write protecting the EFI variable where changing it already requires to boot into an EFI editor is just being dicks, pardon my French. Just let me enable it , I am aware of the risks.
replies(1): >>40725858 #
5. bytehowl ◴[18 Jun 24 05:57 UTC] No.40714466[source]▶
On my Lenovo Legion 5 Pro with i7-13700HX I can disable undervolting protection in stock UEFI. The only problem is that Windows virtualization features get disabled when undervolting is allowed, and I kind of need those.
replies(1): >>40719228 #
6. Scoundreller ◴[18 Jun 24 05:58 UTC] No.40714469[source]▶
I remember some boards, you would have to paint a cpu pin with nail polish to stop it from conducting, or carefully jump one of the several hundred pins on the socket…
7. hmm37 ◴[18 Jun 24 09:33 UTC] No.40715686[source]▶
Many times you can still edit the EFI variable that has been disabled.

https://brendangreenley.com/undervolting-2020-dell-laptops-l...

replies(1): >>40719214 #
8. hu3 ◴[18 Jun 24 14:29 UTC] No.40718273[source]▶
Not trivial but some folks (including me) HEX edit a bit or two from UFEI/Bios to reenable undervolting.
replies(1): >>40719219 #
9. chx ◴[18 Jun 24 15:49 UTC] No.40719214[source]▶
Nope, you can't read please

> for the Comet Lake 10750H processor

That's not 10nm that's just Skylake+++++++++++

10. chx ◴[18 Jun 24 15:49 UTC] No.40719219[source]▶
The laptop BIOS is signed.

I am not exactly unfamiliar with a hex editor but really: you can't.

replies(1): >>40720251 #
11. chx ◴[18 Jun 24 15:50 UTC] No.40719228[source]▶
That's good news, then they reenabled it after three generations of it being disabled.
replies(1): >>40723526 #
12. hu3 ◴[18 Jun 24 17:39 UTC] No.40720251{3}[source]▶
You can disable secure boot. Then edit firmware.

So yes, you can. I did.

13. hmm37 ◴[19 Jun 24 00:35 UTC] No.40723526{3}[source]▶
Perhaps it's just your laptop manufacturer. But people were able to undervolt on gen 11 by editing the EFI variables and then turning off virtualization.

https://old.reddit.com/r/AcerNitro/comments/qvznen/unlock_un...

14. ngneer ◴[19 Jun 24 07:41 UTC] No.40725858{4}[source]▶
I think the trouble is that it is not possible to distinguish (through reliable technical means) a responsible overclocker such as yourself versus an unscrupulous actor editing EFI variables in flash. So, because some bad guys/gals found a way to damage the system, all the good guys/gals suffer as a result, because the system cannot tell them apart. Reminds me of airport security...