i9-14900HX unstable with single core benchmarks but stable multi-core?

[firemustache]

I'm trying to understand why my cpu is stable doing multi core tasking such as benchmarks but I get sometimes
BSOD or other instability issues when doing heavy single core tasks such as single core benchmarks or the known
Lastpass cpu usage issue with Firefox.

Anyone could have an idea of why this could happen?

Below are my current FIVR settings. Current undervolt values are 135mV for Pcore, Pcache and 50mV for Ecache.

Also, I was able to undervolt down to -160mV and run multi core benchmarks with no crash. But single core
benchmarks were crashing 2-3 times as much!

OH... and I forgot to mention... in my Lenovo Legion 7i BIOS, "Current Excursion Protection" is disabled.
I don't know if this option should be enabled or not, but I tried on "enabled" and I'm getting the same
outcomes.

 

[unclewebb]

Anyone could have an idea of why this could happen?

Traditional offset undervolting is a compromise. It reduces the voltage along the entire frequency curve. Your -135 mV undervolt may be stable when the CPU is using the 52 multiplier but this same undervolt is not stable when the CPU is lightly loaded. When 1 or 2 cores are active and the CPU is using the 58 multiplier, your CPU needs more voltage to be stable. When undervolting, not enough voltage is almost always the reason a CPU will crash.

I was able to undervolt down to -160mV and run multi core benchmarks with no crash

At the moment you have a couple of choices. You could under clock your CPU so it no longer ever uses the 58 multiplier. That would mean setting all 8 Turbo Groups to a constant value like 52. You will lose some light load performance but this might let you reliably use your -160 mV undervolt. If you do not do this your other option is to keep reducing your -135 mV undervolt until you reach a point where your CPU is stable at both full load and light load. Both options are not ideal.

What would really be useful is instead of using one offset voltage for the entire voltage frequency curve, what if you could combine your offset voltage with a few tweaks at different frequencies? That is basically what the mV Boost feature does. It adds voltage at 800 MHz to help maintain stability when you use a big offset undervolt. Instead of mV Boost that only handles the offset undervolt problem at one frequency, how about V/F Point Offset tuning that allows some voltage adjustments at multiple frequencies? Your CPU is the perfect candidate for that. You need to be able to add some extra voltage when you are undervolting and the CPU is using the 58 multiplier. Here is a mock-up.

Access to the core and the cache voltage curves individually might also be useful. Never hurts to dream, right?

This is more than just a Photoshop mock-up. This new ThrottleStop feature is actually up and running. Send me a message if you are interested in doing some beta testing. So far everything seems to be working correctly. I do not own a 14900HX so I am not sure what is going to be possible. I have a good feeling that this new feature is going to help people like yourself achieve a more aggressive full load undervolt as well as a more stable part load undervolt. The best of both worlds. The V/F tuning feature is only available on unlocked, 10th Gen and newer, HX and K series processors.

 

[Vya Domus]

CPU achieve higher clocks the fewer cores are under load, it makes sense for it to be most unstable under single core benchmarks.

 

[firemustache]

Traditional offset undervolting is a compromise. It reduces the voltage along the entire frequency curve. Your -135 mV undervolt may be stable when the CPU is using the 52 multiplier but this same undervolt is not stable when the CPU is lightly loaded. When 1 or 2 cores are active and the CPU is using the 58 multiplier, your CPU needs more voltage to be stable. When undervolting, not enough voltage is almost always the reason a CPU will crash.


At the moment you have a couple of choices. You could under clock your CPU so it no longer ever uses the 58 multiplier. That would mean setting all 8 Turbo Groups to a constant value like 52. You will lose some light load performance but this might let you reliably use your -160 mV undervolt. If you do not do this your other option is to keep reducing your -135 mV undervolt until you reach a point where your CPU is stable at both full load and light load. Both options are not ideal.

What would really be useful is instead of using one offset voltage for the entire voltage frequency curve, what if you could combine your offset voltage with a few tweaks at different frequencies? That is basically what the mV Boost feature does. It adds voltage at 800 MHz to help maintain stability when you use a big offset undervolt. Instead of mV Boost that only handles the offset undervolt problem at one frequency, how about V/F Point Offset tuning that allows some voltage adjustments at multiple frequencies? Your CPU is the perfect candidate for that. You need to be able to add some extra voltage when you are undervolting and the CPU is using the 58 multiplier. Here is a mock-up.

View attachment 374427

Access to the core and the cache voltage curves individually might also be useful. Never hurts to dream, right?

This is more than just a Photoshop mock-up. This new ThrottleStop feature is actually up and running. Send me a message if you are interested in doing some beta testing. So far everything seems to be working correctly. I do not own a 14900HX so I am not sure what is going to be possible. I have a good feeling that this new feature is going to help people like yourself achieve a more aggressive full load undervolt as well as a more stable part load undervolt. The best of both worlds. The V/F tuning feature is only available on unlocked, 10th Gen and newer, HX and K series processors.

Wow that is completely amazing! I'm going to message you!

CPU achieve higher clocks the fewer cores are under load, it makes sense for it to be most unstable under single core benchmarks.

That completely makes sense! I never thought of that until this has been mentioned!

(Update)

I just lowered the Turbo boost for 1 and 2 cores from 5.8 to 5.2 GHz as a fast tweak and that seemed
to have resolved the single core loads issue! I'm impressed, but I need to do further testing.

What's more, I think I'll be able to drop even lower the undervolt! I'm gonna play with all this
more in the next hours.

 

[Lew Zealand]

Laptops are designed to be used as is. Dont touch the voltages or the frequencies on your Lenovo Legion 7i, leave everything by default and use a cooling resting plate for heavy work or gaming so it doesn't overheat.

It wont last longer because you undervolt it, neither will it perform better (you might get ~1% perf increase after tweaking for countless hours, which will be unnoticeable in your daily usage). Save yourself the trouble and just use default settings.

You can replace the stock thermal paste for a high end one if you suspect the stock one is of poor quality to optimize the cooling but that's about it.

I disagree, a CPU is a CPU no matter where it's installed. Maybe because I often end up with lower end laptops or Mini PCs, but every laptop CPU gets undervolted to run cooler. If nothing else, it results in less fan noise under load which is always welcome and the primary intent.

Also: Undervolting is fun!

 

[unclewebb]

@N3utro

Your reply and personal opinions about undervolting have nothing to do with the original question that was asked in this thread. Anyone with a hot running laptop can decide for themselves what they want to do about the problem.

 

[N3utro]

@N3utro

Your reply and personal opinions about undervolting have nothing to do with the original question that was asked in this thread. Anyone with a hot running laptop can decide for themselves what they want to do about the problem.

So by your logic if someone asks how to set their chip voltage to 3V nobody should give their opinion about doing such a thing and we should only answer providing technical details on how to do it?

If you dont agree with my arguments it doesn't mean they are not relevant to this topic.

Anyway i didn't come here to start a fight, i've made my point even if some of you dont agree, OP can decide what's the best course of action indeed.

 

[Valour549]

(Update)

I just lowered the Turbo boost for 1 and 2 cores from 5.8 to 5.2 GHz as a fast tweak and that seemed
to have resolved the single core loads issue! I'm impressed, but I need to do further testing.

What's more, I think I'll be able to drop even lower the undervolt! I'm gonna play with all this
more in the next hours.

I recommend setting 1 and 2 core to 5.4 or 5.5 (setting it to 5.2 is on the low side).

Also should tweak the values for the other cores as well, I don't believe any laptop can actually do 5.2 all core (ie. 8 cores), so instead of letting it keep hitting the power limit wall and throttling, it's better to set it to 4.7 to 4.9. Once you run R23 you can see your PKG Power and the FID multipliers on the main screen and you will see if your cores are actually reaching the multipliers you set. If not that means the power isn't enough to sustain them and you should lower it.

You can take a look at my guide. Others have already had very good results.