# Clarifications Undervolting a i7-9750h



## MornesGreatHammer (May 3, 2022)

Hi all,
I've been researching and tinkering with some settings on my Dell G7 7790's i7-9750h, and I'm hitting a mental brick wall. I have a fairly significant turbo limit, and in trying to edge into a more reasonable limit, I am encountering issues with seemingly fairly significant thermal throttling. If I drop the 6 core to 36, I can avoid the problems, but I want to see if there's another way or there is something I am missing. Cinebench r23 multicore score is currently 7204 in these conditions. settings and log attached below. Thanks!

Sidenote; the laptop has had issues with throttling before, so it has been cleaned out and repasted, along with having a permanent residency on top of a book for some elevation for air circulation.


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## unclewebb (May 3, 2022)

MornesGreatHammer said:


> I'm hitting a mental brick wall


It looks like the wall you are hitting is a thermal brick wall.

Keep in mind that Intel gave the 9750H a 45W TDP rating. Dell engineering likely designed a heatsink and fan with this spec in mind. When you decide to run the CPU at 60W and beyond, it is not surprising that the CPU is reaching the maximum safe temperature, 100°C, and thermal throttling to protect against any damage.

You have a couple of choices at this stage. You can design and engineer a more capable heatsink or you can reduce the maximum CPU speed or you can reduce your turbo power limits or you can let your CPU bounce off the 100°C thermal throttling temperature during full load stress testing.



MornesGreatHammer said:


> I want to see if there's another way


Not really. Your undervolt is appropriate and working correctly. There is not much else you can do other than what I listed above. No way to beat the laws of thermodynamics. The inability of your heatsink and fan to dissipate much more than 60W is your limiting factor. The 9750H can go up to 70W or a little beyond but not with your heatsink. It will be forced to thermal throttle if you try to get more speed out of it at full load.

The 60W / 75W MSR limits seem more realistic than having the MSR PL1 and PL2 limits both set to 90W.


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## MornesGreatHammer (May 3, 2022)

unclewebb said:


> It looks like the wall you are hitting is a thermal brick wall.
> 
> Keep in mind that Intel gave the 9750H a 45W TDP rating. Dell engineering likely designed a heatsink and fan with this spec in mind. When you decide to run the CPU at 60W and beyond, it is not surprising that the CPU is reaching the maximum safe temperature, 100°C, and thermal throttling to protect against any damage.
> 
> ...


I've made further adjustments, primarily in increasing the cpu core undervolt, which has yielded good results but is unfortunately unstable, resulting in occasional BSOD's. I'm gonna be slowly pulling into more conservative numbers to find my sweetspot; but I will modify my PL1 and PL2 limits as well! thank you for the feedback


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## unclewebb (May 4, 2022)

MornesGreatHammer said:


> increasing the cpu core undervolt


Some people are stable with the cache at -125 mV and the core offset at -175 mV. Try reducing the cache to -120 mV if this is not stable.


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## LogPap (May 5, 2022)

Hello, i can set the cache votage to: -102,5mv. Everyting above end's with a bluescreen after intense gaming. Core voltage can be increased much lower with stable results. I use a i7 9750h in a MSI g65

Greets


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## unclewebb (May 5, 2022)

LogPap said:


> I can set the cache voltage to: -102,5mv. Everything above end's with a bluescreen


It is all luck of the draw. Some CPUs can undervolt much more than others. 

It is never a good idea to copy and paste someone else's settings you found on the internet. Always best to do lots of testing to find out what works best on your CPU.


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