# i7-8550U undervolt settings



## filterknobber (Jun 13, 2021)

Hi, I'm trying to get the temps down on my ASUS vivobook laptop with i7-8550U and 940MX GPU. I've applied new thermal paste and use a fan base, and the temps are a little better. I have a question about my throttlestop settings though. I can get -118mv on CPU core and cache that is stable with speed shift off running benchmarks, but putting speed shift on anything but 0 crashes. Changing windows power setting doesn't show a change in throttlestop's EPP value. 

I'm wondering if it would be better to leave speedshift off and prioritize around a stable undervolt, or set the speed shift to a setting where it will crash and then test undervolting from there. 

I am also wondering if it's possible to undervolt the 940MX GPU to further help cool the laptop. I haven't been able to access the GPU voltage settings with any software I've tried.


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## unclewebb (Jun 13, 2021)

Other users have told me that it takes a little more voltage to get a CPU stable when Speed Shift is enabled compared to when Speed Shift is not enabled. Setting EPP to 0 keeps the CPU at maximum speed so this is equivalent to having Speed Shift disabled. 

-118 mV is an aggressive undervolt for an 8th Gen U CPU. Are you sure you are 100% stable at that setting? Most similar CPUs are only stable at -80 mV. 



filterknobber said:


> Changing windows power setting doesn't show a change in throttlestop's EPP value.


When testing this, make sure Speed Shift EPP is not checked on the main ThrottleStop screen. When in the Balanced power plan, try moving the task bar power slider back and forth. If the BIOS is not enabling Speed Shift then it is possible that Windows is not Speed Shift aware so it is not able to manage the EPP setting. 

Use whatever settings work best for your computer. It is OK to run your CPU at full speed when idle or lightly loaded. Intel CPUs save power when the individual cores enter the low power C7 state so a fast CPU is not as bad as some people assume. Idle cores in C7 are already sitting at 0 MHz and 0 volts. Hard to improve upon that. 

Many mobile GPUs do not give you access to voltage control. I assume you tried MSI Afterburner?


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## filterknobber (Jun 13, 2021)

Okay, yeah the number changes to 84 when I move the slider. I did try MSI afterburner for the GPU.

I actually wasn't aware of the taskbar slider when in balanced mode. It seems like maybe trottlestop and windows were fighting for speed step control and creating issues. Looking at my notes, I've benchmarked it at -118 with Heaven, Cinebench R23, and the TSbench without a crash, but then at -119 it started freezing.

I'll keep it set to -115, -50 on the intel GPU, speedstep off, PROCHOT off, and the rest set to default for now and try running a game and see if I freeze. I had throttlestop installed a year ago, and remember being able to get 9-11 on TSbench but now I can't seem to get below 16.


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## unclewebb (Jun 13, 2021)

filterknobber said:


> I had ThrottleStop installed a year ago


The TS Bench changed when 10 core support was added. Scores from older versions are not compatible with the latest version. The TS Bench does a bigger calculation now so it takes more time.



filterknobber said:


> benchmarked it at -118 with Heaven, Cinebench R23, and the TSbench without a crash, but then at -119 it started freezing.


It is never a good idea to run a CPU on the edge of stability. I would use -100 mV. That is better than most similar CPUs.

When you undervolt the Intel GPU, did you also undervolt the iGPU Unslice? If you do not undervolt both of these then the Intel GPU undervolt will be ignored. If you have a Nvidia GPU, the Intel GPU is not a significant source or power consumption so there is little to be gained by undervolting it. 



filterknobber said:


> It seems like maybe ThrottleStop and windows were fighting for speed step control and creating issues.


That is definitely a possibility. Best not to use the Speed Shift EPP option in ThrottleStop when using the Windows Balanced power plan.


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## filterknobber (Jun 13, 2021)

I meant Speed Shift not Step in my previous comment. 

I'll keep it around -100 in that case, but now I'm back up to 96* and throttling when I run the TSbench test. Heaven stays around 84-85*, but I'm not sure if that is CPU or GPU. Is there a benefit to using Speed Shift in ultimate performance mode if windows is keeping it set to 0?

I undervolted both the GPU and iGPU unslice the same amount based on what I've read. Any other setting worth experimenting with? Thanks for all your help.

I also have BD PROCHOT unchecked and disable and lock turbo limits checked based on other comments of yours.


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## unclewebb (Jun 13, 2021)

You have a thin and light laptop with a low power 15W CPU. Most manufacturers do not include adequate cooling. If you try to run your CPU continuously at full speed then most of these kind of laptops are going to thermal throttle. The TS Bench is an excessive load for thin and light laptops. Most similar stress tests like Prime95 are even more excessive. Avoid buying laptops like this if consistent full load performance at a reasonable temperature is important to you.

There is no benefit to using Speed Shift if Windows is keeping EPP at 0 and you are happy with EPP at 0. It should not matter one way or the other.



filterknobber said:


> I'm not sure if that is CPU or GPU


The temperature in the red box at the top shows the maximum CPU temperature. If you go into the Options window and enable Nvidia GPU, the box at the bottom will show your Nvidia GPU temperature. You can click on that button for other GPU monitoring data after Nvidia GPU monitoring has been enabled in the Options window.


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## filterknobber (Jun 14, 2021)

Got it, thanks again! The next computer I buy will be a PC whenever GPUs are available again so I don't need to worry about this as much. I am trying to do some audio/video stuff and I want to get things as optimized as possible before I demo software (Ableton Live, MaxMSP, Blender, Resolume, Touch Designer) to see what I am able to run.


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## unclewebb (Jun 14, 2021)

ThrottleStop 9.3.1 has a new feature that allows you to disable all of the C states except for C0 and C1. This can reduce latency and significantly improve SSD 4K read and write times. People that are into music production have been asking for a feature like this for years.


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## filterknobber (Jun 17, 2021)

Is the "on" setting the one I want for music production? I've heard that single core speed is the most important aspect to CPU performance in a DAW.


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## unclewebb (Jun 18, 2021)

filterknobber said:


> Is the "on" setting the one I want for music production?


Most people using their computers for music production like to turn the C states off. This significantly reduces latency but it does have some draw backs. Disabling the C states will eliminate access to the higher turbo ratios so your CPU will run a little slower when lightly loaded and it will also make your CPU run hotter. Usually much hotter if you also decide to toggle C1E off.  

The only way to find out what works best is to try running your software with C states off and try running the same app with C states on. You can also play around with toggling C1E on and off when testing. I do not have access to your hardware or software so you will have to do your own testing.


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