Acer Predator Helios 16 PH16-71 Intel i9 13900HX. Is there any way to allow undervolting?

[Slowbro]

I suppose overclocking too, but let's be honest here, you probably won't succeed greatly at that with a laptop chip! Although that is supposed to be the draw of the HX chips, undervolting + overclocking.

Here's what my FIVR menu looks like:

https://imgur.com/2EGp90V

I've tried anything I can find to enter the "secret BIOS" of my laptop, including holding Fn+Tab while I boot then switching to F2 to enter BIOS, or entering BIOS then shutting it off via power button and pressing F4, 4, R, F, V, F5, 5, T, G, B, F6, Y, H, N, then turning it back on and reentering BIOS, nothing.

I don't feel like I *require* undervolting/OCing, as I feel this CPU is one heck of a beast anyway, but I find it excessively odd that an HX chip is barred from doing what an HX chip is supposed to do? And, hey, undervolting is just great to do. Cuts temps huge.

 

[unclewebb]

The 13th and 14th Gen HX processors respond well to a big undervolt. Keeping them cool after a big undervolt is a lot easier. My 14900HX is stable at -150 mV.

I know how to enter the advanced BIOS on my MSI Vector laptop but that is not going to do you any good.

Searching the internet for your Acer Predator Helios laptop model is mostly dead ends. I found some angry customers that will never buy Acer again because of their decision to lock out CPU voltage control. Sadly I could not find anything for a solution to allow undervolting.

 

[Slowbro]

I think the worst part is a Reddit post where someone inquired about it and in the comments a user said he knew how to do it and just DM him for it. And the account's name? [deleted]!

Commenters joked that Acer must've went after him for it.

I know some users say to follow BrendanGreely's guide for unlocking BIOS but it seems like it's possibly risky. I would really hate to brick my laptop just 'cause I wanted to squeeze efficiency out of it.
I also can't find the proper Intel ME tools---I would need 16.1, and I can't find those anywhere.

I also saw some people say that unlocking their Acer BIOS via the above only allowed overclocking. It seems weird to me that Acer has an impenetrable hardware block on it but uses HX chips? I mean, I guess because even without UV/OC, they're Intel's de facto tops, the highest core counts, highest GHz, etc., but it's weird nevertheless.

 

[Slowbro]

I followed the guide there to adjust the following registers:

CpuSetup "CFG Lock", set to 1 (enabled) initially, manually put it to 0.
CpuSetup "Overclocking Lock", set to 1 (enabled) initially, manually put it to 0.

This enabled ThrottleStop to have a superficial FIVR menu.

https://imgur.com/wVhifmG

Looks like I can make changes, but they don't apply.

Intel's XTU reports that Undervolt Protection is still on, as well:

https://imgur.com/Zg484JK

I saw that in my BIOS, specifically, the CpuSetup register, there was an "Undervolt Protection" address. So I set that from its default of 1 (enabled), to 0.

Changed nothing.

Is it on the CPU microcode itself? There should, logically, be nothing stopping me from undervolting or adjusting my PL1/PL2 at this point.

 

[unclewebb]

Undervolt Protection

The top middle of the ThrottleStop FIVR window also shows that Undervolt Protection is enabled. You can use a positive voltage offset when UVP is enabled but you cannot use a negative voltage offset. This is separate from CFG Lock and Overclocking Lock.

You can try using a small positive offset voltage, +5 mv, just to confirm that ThrottleStop and VBS are set correctly. When you press the Apply button, the + 5mV offset should show up in the FIVR monitoring table immediately.

Other users that have tried to disable Undervolt Protection seem to run into the same problem that you are having. They have found this setting in the BIOS but toggling it on or off does not seem to do anything. I am guessing that there is some sort of secondary setting that also needs to be disabled.

You should be able to adjust the PL1 and PL2 turbo power limits. Undervolting is blocked. Power adjustment should be OK.

Try uninstalling Intel XTU and make sure that there are no XTU remnants still running in the Task Manager when you are done. XTU might be enabling Undervolt Protection after you boot up.

 

[Slowbro]

Interesting. Holy cow, the PL1/PL2 limits were definitely adjustable now after those BIOS changes---although I couldn't say for certain which of the three options it was that helped it!

When I first got the laptop:

https://imgur.com/aNnfYqR

It had a PL1 of 97W. Quite low for a 13900HX.

Now with a PL1 and PL2 of 200W (although due to thermals, it stabilizes at about 150-153W, which to me is still very impressive):

https://imgur.com/dNsiWDt

That's a bit over a 20% improvement!

So you said to apply a minor positive offset voltage? That shows up:

https://imgur.com/K6MBrT6

Quite weird that it'd allow overvolting, but not undervolting, when the former can actually cause damage. The latter, especially with it being runtime (XTU, ThrottleStop, etc.) and not BIOS (requiring a CMOS reset), the worst it can do is cause an annoying BSOD and you go on with your day.

 

[unclewebb]

That shows up:

That confirms that everything VBS related is setup correctly. It is just Undervolt Protection that is holding you back. Intel and some laptop manufacturers are still living in fear of a possible Plundervolt attack.

I love my MSI Vector. I can get it up to 260W without any complaints. When you pay top dollar for a laptop, you should be able to run it however you like. Just imagine how well your laptop would run with a -150 mV undervolt for the core and the P cache like I am using. It runs at a cool 45°C sitting on my lap for light duty stuff like the forums.

It runs like a high end desktop when in balls to the wall mode.

Edit - Not sure if Smokeless would be an option for you.

 

[Slowbro]

It is very odd. I don't regret it for one minute still due to the great screen (although mine isn't the Mini LED panel, it is still very pretty, and swapping the screen out isn't the toughest thing to do if I ever want to, some MSIs also have this as an upgrade option) and---frankly, affordability. I never saw any MSIs come up as used. I saw some Alienwares, AMD and Intel, but no one accepted the offers. Some ASUS as well but I'd be way too afraid to ever get them.

What with the state of US electronics due to, well, tariffs, prices even on the used market are going just nuts. I was getting desperate as the end of April was approaching.

Smokeless is about right as I've never seen anything lack the smoke quite like this:

https://imgur.com/OcLNVuO

I used this same tool on my ROG Ally X handheld to get some extra performance out of it as well, although it had a lot more options there. I do hear Smokeless is generally more aimed toward AMD though, so that makes sense.

So the undervolting block seems to be on the CPU microcode? As I don't think there are any other options in the BIOS for me to adjust with setup_var to do this.

 

[unclewebb]

So the undervolting block seems to be on the CPU microcode?

I don't think so. Other users with 13900HX processors can undervolt without any problems as long as Undervolt Protection is disabled in the BIOS. Hopefully you get lucky someday and find a way to disable UVP.

I have never had the courage to play around with Smokeless. When it works, it looks like it shows the exact same BIOS options that the MSI Advanced BIOS shows. I am lucky and do not need to play around with Smokeless. My MSI laptop has an option to enable or disable Undervolt Protection in the BIOS and it works correctly. It would be interesting to find out if it is changing more than just one setting.

 

[Slowbro]

I used a modified BIOS (using Smokeless Runtime EFI Patcher) that enables the hidden BIOS menu. Undervolt Protection is there and was already disabled due to what I had done earlier. I saw it had undervolting sections for the P-Cores, E-Cores, and some other stuff, but it doesn't appear to do anything.

https://imgur.com/TJqdRSL

30.1k is only 300 points higher than my previous 29.8k (from unlocking the PL1/PL2). I figure it'd be far higher had the -150mV undervolt went through on the P-Cores and E-Cores. I also saw no difference in temperatures or wattage, it was still around 155-158W average during Cinebench.

Acer inferred to me that they allow load-line calibration (LLC) undervolting. I am not sure what that is. I see no options referring to LLC in the hidden BIOS menu---unless the non-functioning P-Core/E-Core options I saw are what that is?
I feel like it's a no, because it seems on point for Acer to allow a bizarre, abstract form of undervolting like LLC (assuming it isn't what I saw in the BIOS), and even overvolting, but not allow normal, easier runtime undervolting.

---

I posted this on a BIOS modding forum as well, but if anyone sees it here and has the technical know-how to address this, I'd love for more to see it.

So some technical stuff that may help if any gifted people want to look at this case:


Undervolt Protection IS an option and CAN be turned off, but doesn’t seem to do anything.
Overclocking Lock IS an option and CAN be turned off. I can’t say for certain if it does anything.
CFG Lock IS an option and CAN be turned off. It 100% works. It is what enables you to adjust your PL1/PL2 of the CPU to whatever you want.


There’s also a feature in the (hidden) BIOS that lets you adjust P-Core and E-Core voltages. I applied a -150 mV undervolt to them, but it didn’t do anything.


So what seems to be happening is this:

• BIOS properly have their options (Undervolt Protection/etc.) that Insyde BIOS (the provider Acer uses) typically have.
• It is capable of “saving” its options for undervolts, I can load that menu right now and see my -150 mV “applied”.
• There seems to be an issue (which I'd say is maliciousness on Acer's part) on boot where DXE or PEI is NOT sending the value (of the undervolt OR the okay to BE undervolted once in runtime) to the CPU via IA32_OC_MAILBOX (MSR 0x150).

I do not know how to look deeper into this last part. But it is the strongest lead I have that it is a failure of the DXE/PEI to either tell the CPU it is being undervolted (if done by BIOS) or tell it that it CAN be undervolted (if done by BIOS OR software).