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Undervolting i7-8750H

MrGrudevMrGrudev Posts: 64Member Devotee
Hi guys,
Because of the high gaming temperatures of my CPU I was looking for solutions. Since now I used my computer with reduced maximum processor state to 90%. That managed to decres the maximum temperature for the CPU from 99 deg to maximum 80 deg (average 60-70 while heavy gaming), but this reduces performance. Now I decided to try undervolting.

I followed the guide for undervolting from another topic from this forum. https://www.youtube.com/watch?time_continue=386&v=N3v3o21M8gg
I tried different values since the guide is for i7-7700HQ (differenct CPU from mine) and I have few questions.

1. What is the average offset voltage for my processor, where I should start testing. (I tried -120.1 mv and get blue screen after about 30 min gaming.)
2. Speed Shift - EEP seems it doent work on my laptop. No difference between 0 and 255 SST. It reaches approximately same FID every time. 
3. Temperatures doest seems to decrease significantly. I managed to reduce them to around 70 on both CPU and GPU, after reducing the Turbo Ratio Limits and Multiplier from 41 to 32 ( decrease the Boost from 4.1 Ghz to 3.2 Ghz.)
4. And finally how can I check my system stability? Any benchmark tools or just gaming, until I get Blue screen :D 

If you have suggestions what settings will suits my CPU best, please help.

Thank you in advance!

Best Answers

  • Queen6Queen6 Posts: 319 Skilled Practitioner
    Accepted Answer
    What model, what software have you tried to undervolt the CPU?  99C is high for the i7 8750H, majority of notebooks will spike into the 90C range, then reduce temperature to mid 70's or lower. i7 8750H reacts little differently compared to the i7 7700HQ, equally from my experience it can still benefit from undervolting, with the major being the reduction in power consumption.

    i7 8750H with -140mV undervolt applied 100% stable.  No thermal throttling, similar to other i7 8750H notebooks performance will roll off after the PL-2 limit, admittedly it's good silicon and a robust cooling solution.

    Right now you should set everything back to stock, if ThrottleStop just delete the throttlestop.ini file and fully shut down the notebook.  Then only set a CPU Core and CPU Cache of -100mV, and take it from there, too many changes make it difficult to verify any change & effect.

    Personally I Use ThrottleStop's 8.60 TS Bench and OCCT for stability testing and keep everything else down to the minimum, if the system BSOD and is writing data it may become corrupted.  The TS Bench 1024M stress test is excellent at revealing errors without crashing the system, although a little time consuming I run it in sets of 3, 6 & 9 following with OCCT.  In my experience 30 minutes stability test with OCCT CPU (Large Dataset) is enough, if stable then you can proceed with a 3-4 hour stability test.

    Q-6
  • Queen6Queen6 Posts: 319 Skilled Practitioner
    Accepted Answer
    MrGrudev said:
    One more question. Undervolting the CPU -100.6 seems to be stable. I tried -105.5, game (Forza 3) crashed but not the whole system. Only the game crashed and shut down. Is this because of the undervolting or is it just the game?
    Play the game again without the undervolt that will help to confirm one way or the other.  For me the system has always locked up requiring a restart if the undervolt  is too deep.

    Q-6
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FAQ & Answers

  • asad814asad814 Posts: 324Member Skilled Practitioner
    edited June 22
    you can start offset from -100 mv and go above(adding -1mv) until you see blue screen.......dont do stress test as it will push cpu to the limits i advise you to game for 30 to 50 min to check stability.......i have i7 6700hq and i undervolted to (-129mv) i havnt done any stress test just play games for some hours and it was fine
  • SkelomorphSkelomorph Posts: 463ACE Pioneer
    1. For undervolt as asad said, start at -0.100 and see if crashes still occur. Then you can slightly raise it if they do not. If they do, try -0.080.

    2. Don't worry about Speed Shift too much. It will have very little to zero affect on temperatures. Speed Shift more or less controls performance. So the trade off here would be laggier games, again not worth it.

    3. Turning off turbo is against the point of having a good CPU in the first place. I don't see the trade off worth it. 

    4. There are multiple benchmark tools. Unigine Heaven Benchmark, Prime95, and 3DMark are all good benchmark utilities.

    Let me ask this first. A temp of 99C typically means there is something wrong. I have never had my laptop get that hot even with factory thermal paste and with restricted airflow. If a singular undervolt can't lower the temperature, then it needs repasted.

    Something else you may need to do is update BIOS.

    Skelo
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  • MrGrudevMrGrudev Posts: 64Member Devotee
    Now I followed another guide for undervolting, this time for my processor. The guy from the guide undervolted his processor -.125. 
    I tried with .125 and now no crashes, but it reduces the performance. Now I get lower FPS with no matter what Multiplier and Turbo Rating limmit.... It doesnt make sens. Only temperatures goes up when I increase multiplier and turbo rating....
  • asad814asad814 Posts: 324Member Skilled Practitioner
    undervolting does not effect the performance mine is working fine after undervolting....if your laptop is old then you can try cleaning dust from fans as they also cause overheating and performance issues
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    Accepted Answer
    What model, what software have you tried to undervolt the CPU?  99C is high for the i7 8750H, majority of notebooks will spike into the 90C range, then reduce temperature to mid 70's or lower. i7 8750H reacts little differently compared to the i7 7700HQ, equally from my experience it can still benefit from undervolting, with the major being the reduction in power consumption.

    i7 8750H with -140mV undervolt applied 100% stable.  No thermal throttling, similar to other i7 8750H notebooks performance will roll off after the PL-2 limit, admittedly it's good silicon and a robust cooling solution.

    Right now you should set everything back to stock, if ThrottleStop just delete the throttlestop.ini file and fully shut down the notebook.  Then only set a CPU Core and CPU Cache of -100mV, and take it from there, too many changes make it difficult to verify any change & effect.

    Personally I Use ThrottleStop's 8.60 TS Bench and OCCT for stability testing and keep everything else down to the minimum, if the system BSOD and is writing data it may become corrupted.  The TS Bench 1024M stress test is excellent at revealing errors without crashing the system, although a little time consuming I run it in sets of 3, 6 & 9 following with OCCT.  In my experience 30 minutes stability test with OCCT CPU (Large Dataset) is enough, if stable then you can proceed with a 3-4 hour stability test.

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee

    3. Turning off turbo is against the point of having a good CPU in the first place. I don't see the trade off worth it. 

    Agree, thats why I want to reduce the temperature somehow, without sacrificing performance. But maximum temps fo up to 99 deg... something should be done.

    asad814 said:
    undervolting does not effect the performance mine is working fine after undervolting....if your laptop is old then you can try cleaning dust from fans as they also cause overheating and performance issues
    The laptop is 1 month old.. The dust couldnt be the problem.

    @Queen6 I get this temperatures since I got the laptop. When I unpacked it, I installed few games - Assassins creed Origin, Tom Clancy Ghost Recon, Far Cry 5... They are all heavy games. When playing this games, CPU maintains temperatures 75-99, with lots of ups and downs. Average lets say 80-85 degrees. And of course the CPU throttles a lot, resulting in fluctuation of FPS. I have a feeling that the CPU uses Turbo even it is not needed sometimes. 
    Then I reduced the maximum processor state to 90% and managed to reduce the temperatures to steady 60-65 degrees, but this disables Turbo and reduces the maximum frequency of the CPU to 1.9 Ghz.

    Queen6 said:
    What model, what software have you tried to undervolt the CPU?  99C is high for the i7 8750H, majority of notebooks will spike into the 90C range, then reduce temperature to mid 70's or lower. i7 8750H reacts little differently compared to the i7 7700HQ, equally from my experience it can still benefit from undervolting, with the major being the reduction in power consumption.

    i7 8750H with -140mV undervolt applied 100% stable.  No thermal throttling, similar to other i7 8750H notebooks performance will roll off after the PL-2 limit, admittedly it's good silicon and a robust cooling solution.

    Right now you should set everything back to stock, if ThrottleStop just delete the throttlestop.ini file and fully shut down the notebook.  Then only set a CPU Core and CPU Cache of -100mV, and take it from there, too many changes make it difficult to verify any change & effect.

    Now I undervolted with Throttlestop. Later I will return everything back to normal, undervolt and post a printscreen of the temperatures.I tried this, maintains above 80 degrees.
  • MrGrudevMrGrudev Posts: 64Member Devotee
    Returned everything to normal and undervolting by -0.100 resulted in temperatures minimum 84, maximum 92degrees while playing Assassins Creeds Origin. These temperatures was reached as soon as I started loading the game, even before I start playing.

    P.S. Same conditions before undervolting, temperatures was 90-99 degrees, so undervolting reduced it a little, but not enough I think.
  • asad814asad814 Posts: 324Member Skilled Practitioner
    so the only thing is now is to change the stock thermal paste with a good one....this will reduce tempts by 10-20C...if the laptop is under warranty then send it to acer otherwise you can do it by yourself
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    What limits is the CPU tripping in ThrottleStop? is the notebook elevated, if not raise the rear and inch or so.

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee
    The processor is working perfectly, maintaining 3.9-4.1 Ghz while gaming, performance is excellent. The only problem is as you can see the temperature.
    I am not sure if I understand your question @Queen6

    The notebook is elevated about 3-4 cm from the desk.
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    edited June 22
    Look at the limits in ThrottleStop, it will open another window.  If you want to reduce the temperature, you'll likely need to reduce the Turbo Ratio Limits in FIVR, try reducing all by a factor of 2, this will reduce CPU frequency and power consumption, ultimately temperature.  You can set up a profile in ThrottleStop for gaming with reduced Turbo Ratio Limits.

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee
    As I said before I tried with different options. I reduce both Turbo Ratio limits and the Multiplier by same value. Now as you advice me reset all settings and only undervolted the Cpu core and cpu cache by 0.100. Which means that the Turbo Ratio Limits are 41 for core 1 and 2 ; 40 for 3 and 4 and 39 for 5 and 6.
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    You either have to increase cooling, reduce power consumption, reduce performance, or live with the operating temperature.  Have you tried increasing the undervolt to -110mV and testing it?  Deeper you can go the better, as the reduction in voltage will also proportionally reduce CPU power consumption & heat.

    You can also consider undervolting the GPU as this will also help to reduce the temperature as very likely it's a shared cooling system.  Key is striking a balance where user performance is not compromised, which in general means step by step.  Replacing the TIM is an option, equally it will likely void warranty

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee
    I will try reducing the voltage more and more, maybe will limit the Turbo boost a little until the average temperatures drop to about 70-75. 
    Yesterday it crashed on -120.6 and Turbo limites to 3.2. Later I tried -125 without limiting the turbo and it was stable...
    Thank you all for the support.
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    Take your time, step by step, this way you will know exactly what to revert to if the OS becomes unstable.  Your being pretty aggressive looking for 70C may be possible with the GPU undervolted and lower ambient temp.  I'll find the point of stability, then pull the undervolt back 10% as I'm more stability focused nor does it generally impact performance.

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee
    One more question. Undervolting the CPU -100.6 seems to be stable. I tried -105.5, game (Forza 3) crashed but not the whole system. Only the game crashed and shut down. Is this because of the undervolting or is it just the game?
  • Queen6Queen6 Posts: 319Member Skilled Practitioner
    Accepted Answer
    MrGrudev said:
    One more question. Undervolting the CPU -100.6 seems to be stable. I tried -105.5, game (Forza 3) crashed but not the whole system. Only the game crashed and shut down. Is this because of the undervolting or is it just the game?
    Play the game again without the undervolt that will help to confirm one way or the other.  For me the system has always locked up requiring a restart if the undervolt  is too deep.

    Q-6
  • MrGrudevMrGrudev Posts: 64Member Devotee
    Yes, I taught so. Thanks @Queen6
  • laxmanballaxmanbal Posts: 3Member New User
    Did you find a solution of heating bro?
  • MrGrudevMrGrudev Posts: 64Member Devotee
    Hi,

    Currently I undervolted the Core and Cache by -135 mV and Intel GPU -0.50 mV. That way I managed to maintain 3.9 on all cores at about 45-49W. (see picture below) Never reaches 56 limit. Still get a little bit of throttle on bechmarking after 28 sec, but it is negligible. Dropping the power to 45W reduces the frequency to 3.8 GHZ, which may be maintained for a long period of time. Just for comparison, before the undervolting I was unable to get 3.9 even on 56W. Playing games is not a issue because the power demand is lower than benchmarking and it stays at 3.9 the whole time.
    Also I use cooling pad, which btw does nothing besides lifting up the notebook. Its fan is just weak.
    On that configuration my temperatues go as high as 80, with occasional spikes to 85 max.

    To further reduce the temperatures I made my second Throttlestop plan called "Games".  Again undervolted by -135 mV. There I set the Turbo ratio limits to 3.4, sometimes increase it to 3.6... Never exceeds 75 degrees and actualy there is no impact on performance. Looks like the CPU is more powerful than most games need...
    Most of the time I use this plan.

    P.S. Speed Shift seems to do nothing.. No difference between 0 and 41 (41 is max on  this CPU)


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