Intel and OEMs have killed undervolting and there is little that you can do about it

[Redaktion]

Undervolting is dead. Worse still, OEMs are killing the functionality on older machines too. Undervolting is no longer possible on recent Dell XPS laptops, for example, nor on the Surface Laptop 3 or Surface Pro 7.

https://www.notebookcheck.net/Intel-and-OEMs-have-killed-undervolting-and-there-is-little-that-you-can-do-about-it.477330.0.html

[Omri]

Undervolting didn't do the trick for me in bringing temperatures down, lowering TDP have MUCH more effect in that.

[slyh]

SGX is not an instruction set for undervolting. It allows software to create an enclave memory. Plundervolt bypasses the protection by undervolting the processor.

[dasdasdas]

I guess now people can shut up cause this vulnerability is fixed. No matter the CPU is 100 degrees, important thing is that it doesn't have this vulnerability anymore. Yeah. Right. Like someone would try to steal something from 10yo kid playing gta 5 downloaded from torrent using this vulnerability. Plain stupid.

[Anonym]

In summary, Plundervolt exploits Intel Software Guard Extensions (SGX), which is a set of instruction codes that undervolting programs like Throttlestop and XTU use to manipulate CPU voltages.

This is flat out wrong. While undervolting allows an exploit similar to spectre over the data in SGX enclaves, undervolting DOES NOT by any means use SGX instructions (but rather manipulates the MSRs directly).

Furthermore, because Intel SGX is optional and actually requires flicking a toggle in the BIOS to enable it, there is no sense in disabling undervolting if Intel SGX is also disabled.

It's baffling that the people in charge of reporting this don't do their homework to actually understand the sheer stupidity of the fix.

[Lucas]

From what I understand this applies when Intel XTU or Throttlestop is used, right? What about desktop cpus undervolted using the motherboard bios?

[S.Yu]

WTF? At least it's not a Windows update so I could refuse to install it right?

[EHitardo]

Undervolting was the thing which avoided me to return my Asus GL502VMK (i7-7700HQ with a NVidia GTX 1060 6GB).

So, if Asus and Intel are not allowing me to do that, I will certainly test my next laptop to the limit, and will certainly return it if temperatures are 95ºC+, on both the CPU and GPU.

Thus, OEMs, be aware!
Undervolting was the thing that allowed users to keep their machines running in good conditions.
Without it, you must produce more quality laptops, with better cooling solutions.

After all, it is one more reason to go Ryzen.

[Lucas]

@EHitardo

The worse thing is that the cooling solutions will most likely be worse as Ryzen runs cooler and most users are not on enthusiast level to test it so thoroughly.

[XMG Community]

Not all OEMs are alike. We still allow Undervolting in most of our Comet Lake H models.

Our current overview can be found here:

https://www.reddit.com/r/XMG_gg/comments/h0wuoh/cpu_undervolting_in_bios_setup_for_xmg_and/

// Tom

[Ascaris]

Undervolting is not dead, and there definitely is something we can do about it. I own my machine; Intel and Dell do not. 

Those of you who run Windows 10, beware if you have not yet received the firmware update that disables undervolting. Some OEMs, like Dell, have had MS push out the firmware update to be installed automatically (as Windows 10 is prone to do). Disable firmware capsule updates in the UEFI (it may be called something else for non-Dells) before this "fix" infects your laptop. 

My Dell G3 has an option in the UEFI to enable "BIOS" downgrades, and there was nothing on the Dell site about the 1.12 update being irreversible, so I went ahead and installed it manually. My temperatures increased, and I realized eventually that my undervolting had been un-applied. After doing some reading to figure out why, I tried to revert the firmware to 1.11, but I was told (at the very end of the flash attempt) that it was an "unsupported downgrade," and it did not work.

Dell, if you have a checkbox to allow downgrades, it should have the effect of allowing downgrades. If that box is checked, and it was, I don't want to hear about any downgrade being unsupported. I didn't ask you to support it... I told you to do it.

There are ways to defeat this, with some Dells at least. I'm using the same Dell laptop I mentioned above, on the 1.11 firmware, and nicely undervolted to write this. Although my G3 is not the same model or series, I used vgtrong's guide at Reddit and on Youtube, and it worked. Note that the error messages about the management update failing, and the other error messages after that, do not mean it failed. The video shows the same failures, but it did roll back to 1.11 regardless. Remember to then enter the UEFI settings and revert to factory defaults, then rebuild all of your personal settings. Underclocking should hopefully work at that point.

Some people with other models of Dell have reported downgrading without any "unsupported" nonsense.

I am all for security fixes, all else being equal (that was why I installed the 1.12 update manually), but in this case, all else is far from equal. "Plundervolt" poses no threat to me, as I do not use SGX or even have it enabled, so a fix that addresses a nonexistent problem at the cost of eliminating a valuable feature is not a worthwhile tradeoff.

I'll have to continue to monitor any microcode updates to see if they have the effect of disabling undervolting by themselves. I'll roll it back if it ever comes to be.

[Ascaris]

Not all OEMs are alike. We still allow Undervolting in most of our Comet Lake H models.

Tom, that's fantastic, thanks for that!

My Dell G3 is my first gaming laptop, and I had not really considered undervolting until quite recently. It was not a concern when I bought the G3, but now that I know what I do now, it will certainly be a box that must be ticked prior to any future Intel laptop purchases (gaming or otherwise). I'd rather that OEMs like Dell do as you have done, to include undervolting controls in the UEFI setup, and if they are as complete and useful as the software controls, I'd be fine with the MSRs being restricted from userspace for security reasons.

[Atharv]

UNDERVOLTING WILL STAY INOUR HARST BUT SERIOUSLY WHY THE HECK DID INTEL DO THAT. IF YOU DOWNLOAD SOME RANDOM EXPLOIT THATS YOUR PROBLEM SMH. MY I5 9300H IS EUNNING 43DEGREES IDLE BECAUSE OF MY LORD AND SAVIOR THEOTTLE STOP BUT INTEL PLANS TO DEATROY IT. HECK NAHHH