# Undervolting core i7 8665u on Dell possible with Intel XTU but not with Throttlestop



## hitsov (Sep 8, 2020)

Hi,

I am able to undervolt my latitude 7400 (which really badly needs it) with Intel XTU but not with Throttlestop. I really prefer the light interface of Throttlestop and the feature to disable the undervolt while in sleep mode since now if I undervolt with XTU it restarts after every sleep. In Throttlestop it takes the undervolt, it shows in HWMonitor, but its not really applied, see below (-1000 mV undervolt):





Am I missing something? I was able to use Throttlestop on my Acer and that worked like a charm.
Thanks in advance!

Greets,
Ivo


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## Joel Santos (Sep 8, 2020)

I have the same problem, in my case, cache voltage works but changing core voltage doesn't work, can also put -1000mv, still waiting for answer in my post


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## AOne (Sep 8, 2020)

After some value for the Core, the setting is simply ignored. If you use the right value (up to approximately 2:1 ratio), all should be fine. Anyway, the CPU Cache undervolt seems to be the one that matters the most.


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## hitsov (Sep 8, 2020)

I can undervolt the core with XTU until it BSOD-es, the magic value with me is around 110mV. With Throttlestop nothing happens, no effects on power consumption either.


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## Joel Santos (Sep 8, 2020)

AOne said:


> After some value for the Core, the setting is simply ignored. If you use the right value (up to approximately 2:1 ratio), all should be fine. Anyway, the CPU Cache undervolt seems to be the one that matters the most.



Yeah i have read this many times, and again, by watching the voltages, lower core voltage than cache does absolutely zero, i tried 2:1 , other bioses, just try it by yourself and you will see i'm right


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## unclewebb (Sep 8, 2020)

@hitsov - Your screenshot shows that you only undervolted the core. The adjuster in XTU adjusts both the core and cache at the same time and sets both voltages to the same values. In ThrottleStop, you need to adjust the core and cache offset voltages individually. If you use ThrottleStop and only adjust the core offset, the CPU will ignore this request.





@Joel Santos - Did you try testing with Cinebench R20? Some software will show zero benefit when adjusting the core to a higher number compared to the cache. It depends on the software and what CPU instructions the software is using. Cinebench R20 has shown positive results. Older software like Cinebench R15, no difference. Newer games have also shown positive results.

Core -122 mV & Cache -122 mV








						Cinebench 122.png
					






					drive.google.com
				




Core -160 mV & Cache -122 mV








						Cinebench 160.png
					






					drive.google.com
				




Core -210 mV & Cache -122 mV








						Cinebench 210.png
					






					drive.google.com
				




A long time ago I decided to rewrite ThrottleStop so the core and cache voltages were always in sync. I wanted ThrottleStop to be just like XTU. The complaints came back to me immediately. I went back to the old way so users can adjust these voltages individually if they want to. If you see no benefit doing this, set them both equally.


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## AOne (Sep 8, 2020)

I'm with such settings and it works, though with different CPU. Would not recommend something if haven't tried it myself.


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## hitsov (Sep 8, 2020)

@[B]unclewebb[/B]*, believe it or not, I was just returning to write the solution! Indeed, I was able to undervolt both the CPU and the iGPU by giving the same values for the CPU and case and the same values for iGPU and iGPU unslice. Thank you so much!*


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## Joel Santos (Sep 8, 2020)

unclewebb said:


> @hitsov - Your screenshot shows that you only undervolted the core. The adjuster in XTU adjusts both the core and cache at the same time and sets both voltages to the same values. In ThrottleStop, you need to adjust the core and cache offset voltages individually. If you use ThrottleStop and only adjust the core offset, the CPU will ignore this request.
> 
> View attachment 168066
> 
> ...



Okay after further testing you are right, up until -215mv/-225mv core voltage works, i see voltage goes down, after that it seems like it does nothing but i feel like i could still bring it lower than this, is this a bug in the software or it's just the cpu's that won't accept more undervolt?

This is what i get in R20 at -250mv in core


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## unclewebb (Sep 9, 2020)

Joel Santos said:


> is this a bug in the software


ThrottleStop works fine. These are voltage requests that you are sending to the CPU. The CPU gets to decide whether to use or ignore your request. The first picture in this thread shows that if you request a -1000 mV offset voltage and you only send this request to the core and not the cache, your request will be ignored.

Same thing happens if you set the core way beyond what the cache is set to. Setting the core offset to -200 mV or -225 mV is OK. Going beyond that is ignored by the CPU.

No one knows the exact relationship. Intel XTU does not allow you to adjust these two voltages independently so there is no documentation available from Intel to confirm that this works or why this works. The only proof is user testing.

One theory on reddit is that there seems to be a 2:1 ratio as the max. If you adjust the cache to -100 mV, then you can adjust the core offset to -200 mV. A user contacted me just recently and he disagrees with that theory. His 10th Gen CPU is very cache limited. He can only run his cache reliably at -60 mV but his Cinebench scores continue to improve as his core offset goes from -120 mV until -200 mV.

It seems that newer software that uses the AVX instructions benefits most from running different voltages.


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## AOne (Sep 9, 2020)

Your CB20 scores are the best I've seen so far for this CPU.


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## Joel Santos (Sep 9, 2020)

unclewebb said:


> ThrottleStop works fine. These are voltage requests that you are sending to the CPU. The CPU gets to decide whether to use or ignore your request. The first picture in this thread shows that if you request a -1000 mV offset voltage and you only send this request to the core and not the cache, your request will be ignored.
> 
> Same thing happens if you set the core way beyond what the cache is set to. Setting the core offset to -200 mV or -225 mV is OK. Going beyond that is ignored by the CPU.
> 
> ...



Thanks, yeah this is what i noticed, sadly i can't let the cpu use more than 50w or the temps just go to 85-90c all the time while gaming (i always test BF V Fps uncapped to see how temps are), the cooling on the Y540 is just not that great , it's a thin laptop, i'm more surprised by the Rtx 2060 that barely goes over 65c while the cpu is cooking eggs, anyways it's great to see the performance is there if i need, but for gaming i might just do a profile to limit the cpu power to 30-35w so i can just game comfortably in the 60-70's C range without worrying about temps too much, I've done some testing and the fps change is very little, the screen is also 60hz so no need for extra power.



AOne said:


> Your CB20 scores are the best I've seen so far for this CPU.



Appreciated  just closed most background apps.


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## AlkalineKnight (Dec 27, 2020)

hitsov said:


> Hi,
> 
> I am able to undervolt my latitude 7400 (which really badly needs it) with Intel XTU but not with Throttlestop. I really prefer the light interface of Throttlestop and the feature to disable the undervolt while in sleep mode since now if I undervolt with XTU it restarts after every sleep. In Throttlestop it takes the undervolt, it shows in HWMonitor, but its not really applied, see below (-1000 mV undervolt):
> View attachment 168046
> ...


I have a Lat 7300 and am trying to get more out of the CPU as when I run Cinebench I am getting throttled back to 2.73Ghz across all cores even though I have made some recent modifications that ensure my CPU is more efficiently cooled. Did you get any luck with increasing the performance of the this CPU? 
Cinebench R23 (Score 3493)


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## unclewebb (Dec 27, 2020)

@AlkalineKnight - If you have some ThrottleStop questions, have a look in the ThrottleStop section.









						ThrottleStop
					

Optimize and tweak your Intel processor




					www.techpowerup.com
				




Start a new thread there and post lots of pictures of how you have ThrottleStop setup. Also include a ThrottleStop log file while gaming or using your computer.

The U series are powerful CPUs if the manufacturer leaves the power limits unlocked. Dell tends to lock their laptops and might also force a low turbo power limit. The log file is a good way to see what is going on during normal use and if there is any throttling.

Try running Cinebench R20. Same as R23 but a little quicker to get results.








						MAXON Cinebench (R20.0) Download
					

CINEBENCH is a real-world cross platform test suite that evaluates your computer's performance capabilities. CINEBENCH is based on MAXON's award-winn




					www.techpowerup.com


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## hitsov (Dec 27, 2020)

AlkalineKnight said:


> I have a Lat 7300 and am trying to get more out of the CPU as when I run Cinebench I am getting throttled back to 2.73Ghz across all cores even though I have made some recent modifications that ensure my CPU is more efficiently cooled. Did you get any luck with increasing the performance of the this CPU?
> Cinebench R23 (Score 3493)


Hey,

I definitely managed to squeeze out a lot more power out of it. In order to do that I did 90 mV undervolt on the CPU and the iGPU, the iGPU can go to -125mV but I didn't see much benefit. The CPU can also do -100mV but its not completely stable. Another thing that I did was to apply good thermal interface compound from thermal grizzly. First I did the Thermal grizzly kryonaut, which was a huge improvement, then I went all out and did liquid metal (conductonaut), which was better, but not a huge improvement.
Before the CPU couldn't sustain more than 8-12 W total package power, now I can sustain 22W all day long, not exaggerating. The 22W is actually a dell imposed limiter, so you cant go around that. When you first load the CPU it does 40+ W, but after 20 seconds or so it limits it to 22W. Still its quite alright.
I limited the single core to 4.5 Ghz because otherwise its too hot and you dont get much gain out of it. For the multiple cores I limited it to 4.2 Ghz, which is OK, but when the 22W limit kicks in it throttles down to 3.3 Ghz sustained. Cinebench R23 score is 4136 points. The fan takes 2 minutes to kick in during the test.
Overall huge improvement, also the fan is not going off like crazy with the new compound and the throttlestop compared to stock. I hated this laptop, now I love it.
I hope this helps, let me know if you want me to post some config details.

Greets,
Ivo


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## AlkalineKnight (Dec 27, 2020)

hitsov said:


> Hey,
> 
> I definitely managed to squeeze out a lot more power out of it. In order to do that I did 90 mV undervolt on the CPU and the iGPU, the iGPU can go to -125mV but I didn't see much benefit. The CPU can also do -100mV but its not completely stable. Another thing that I did was to apply good thermal interface compound from thermal grizzly. First I did the Thermal grizzly kryonaut, which was a huge improvement, then I went all out and did liquid metal (conductonaut), which was better, but not a huge improvement.
> Before the CPU couldn't sustain more than 8-12 W total package power, now I can sustain 22W all day long, not exaggerating. The 22W is actually a dell imposed limiter, so you cant go around that. When you first load the CPU it does 40+ W, but after 20 seconds or so it limits it to 22W. Still its quite alright.
> ...


Hi Ivo,

Thank you for the swift reply. I apologise for asking, however I get myself a little lost inside of Throttle Stop. At one point I was able to get a boost clock of 4.6Ghz out of my laptop and now it will not increase past 4.2Ghz. I believe that this is because along the way I have done something without understanding the implications fully. Are you able to share your configuration profiles for your setup so that I can use it as a reference?

I performed the -90 mV on the CPU and CPU cache and performed the -125 on the iGPU, but not seen the improvement. So I think I must of done something wrong. I am running an external GPU so I am not fussed about the performance of the iGPU. So ideally I would love to dedicate majority of the Watts to the CPU. I've noticed that it locks back 22w, 23w at a push after 10 seconds inside Cinebench. 

Finally I am also not concerned about the cooling as I have modified the cooler on my laptop so that when I am gaming I never exceed 65 degrees Celsius across all cores. Under stress loads of Cinebench I flatten out at 2.73Ghz across all cores with average core temps of 51 degrees Celsius. 

Any further help would be greatly appreciated.


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## hitsov (Dec 28, 2020)

AlkalineKnight said:


> Hi Ivo,
> 
> Thank you for the swift reply. I apologise for asking, however I get myself a little lost inside of Throttle Stop. At one point I was able to get a boost clock of 4.6Ghz out of my laptop and now it will not increase past 4.2Ghz. I believe that this is because along the way I have done something without understanding the implications fully. Are you able to share your configuration profiles for your setup so that I can use it as a reference?
> 
> ...


Hi,

Here are my settings:






Make sure to:
Set the same undervolt for the CPU core and cache, same for the iGPU and the iGPU unslice
Check the checkboxes for sleep defaults, otherwise the laptop restarts when it goes to sleep
Make sure to disable speed shift, otherwise the CPU maxes at 4.2 GHz for some reason


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## AlkalineKnight (Dec 29, 2020)

hitsov said:


> Hi,
> 
> Here are my settings:
> View attachment 181402
> ...


Thank you. Really appreciate your response. Have you made any adjustments inside of TPL? Mine is set to as follows.
Since configuring the above I achieved 3458 in Cinebench R23. My previous achievement was 3629.


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## hitsov (Dec 29, 2020)

Hi,

That's what my TPL looks like. Is your CPU the same?




Do you actually see the undervolt in HWMonitor?


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## AlkalineKnight (Dec 29, 2020)

hitsov said:


> Hi,
> 
> That's what my TPL looks like. Is your CPU the same?
> View attachment 181471
> ...


No, HWmonitor does not show the undervolt.

So it would seem that ThrottleStop is being blocked from making changes. Knew something was not right. Although I mainly thought it was me more than the software.

I managed 3825 by increasing the ICC Max to 128.


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## Caring1 (Dec 29, 2020)

AlkalineKnight said:


> Any further help would be greatly appreciated.


It was suggested you go to the Throttlestop thread for further assistance.








						ThrottleStop
					

Optimize and tweak your Intel processor




					www.techpowerup.com


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## AlkalineKnight (Dec 29, 2020)

Caring1 said:


> It was suggested you go to the Throttlestop thread for further assistance.
> 
> 
> 
> ...


Thank you and Appreciate the invite by both yourself and unclewebb my reason for continuing in this thread with hitsov is that he has near the exact same edition as my system and all that I have read through ThrottleStop's guides and other threads do not seem to work. I cannot explain why, unless Dell has locked things further down since their latest BIOS.

At this point I do not believe another thread will help as none of the parameter changes I am making seem to be making any difference. Unless I another member has the exact same model and edition as the laptop I am using  and has come across this.

My last resort and something that I am looking into the theory of using RWeverything to reinstruct the process to hold the boost state for longer or hard set the frequency and multiplier as Temperature has been ruled out as an issue.


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## bogmali (Dec 29, 2020)

Caring1 said:


> It was suggested you go to the Throttlestop thread for further assistance.
> 
> 
> 
> ...



Or I can just move it to the TS forum


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## hitsov (Dec 29, 2020)

AlkalineKnight said:


> No, HWmonitor does not show the undervolt.
> 
> So it would seem that ThrottleStop is being blocked from making changes. Knew something was not right. Although I mainly thought it was me more than the software.
> 
> I managed 3825 by increasing the ICC Max to 128.


Go to BIOS and reset to factory defaults (2nd option). That did the trick for me, otherwise the undervolt was locked.


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## unclewebb (Dec 29, 2020)

AlkalineKnight said:


> HWmonitor does not show the undervolt.


The latest version of ThrottleStop makes it easy to see when CPU voltage control is locked. 
If the FIVR monitoring table is reporting +0.0000 from top to bottom in the Offset column, the voltages are locked.









						ThrottleStop 9.2.9
					

ThrottleStop 9.2.9 https://www.techpowerup.com/download/techpowerup-throttlestop/  New Features - added 10850K / 10900K support including a new Turbo Group access window. - updated the TS Bench and the C State window for the 10 core CPUs. - enabled Limit Reasons support for Comet Lake CPUs. -...




					www.techpowerup.com


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## hitsov (Dec 30, 2020)

Hey @unclewebb, I really love Throttlestop, but I have a small problem with it. Upon normal restart of windows Throttlestop sometimes thinks its abnormal restart and resets the voltages and I need to set the voltages manually. If I manually close all programs before restart that usually helps. Is it possible to restore voltages with the click of a button or something similar?


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## unclewebb (Dec 30, 2020)

@hitsov - The last screenshot you posted shows this.






You are telling ThrottleStop not to save your voltages until after you exit ThrottleStop. If you have done some testing and your voltages are stable, switch to the last option.

"OK - Save voltages immediately" should solve your problem.


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## hitsov (Dec 30, 2020)

Thank you @unclewebb! TS is the best thing after sliced bread!


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## AlkalineKnight (Dec 30, 2020)

unclewebb said:


> The latest version of ThrottleStop makes it easy to see when CPU voltage control is locked.
> If the FIVR monitoring table is reporting +0.0000 from top to bottom in the Offset column, the voltages are locked.
> 
> 
> ...


Thank you UncleWebb.

I defaulted my BIOS and upgraded to the Beta and now near enough all of my FIVR view is greyed out. The only plus side I now have is that HWmonitor is registering 4.8Ghz boost clocks once more. Is there any light at the end of the tunnel or should I now admit defeat...?



hitsov said:


> Go to BIOS and reset to factory defaults (2nd option). That did the trick for me, otherwise the undervolt was locked.


Hi Hitsov, could you confirm what BIOS version you are running?


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## hitsov (Dec 31, 2020)

AlkalineKnight said:


> Thank you UncleWebb.
> 
> I defaulted my BIOS and upgraded to the Beta and now near enough all of my FIVR view is greyed out. The only plus side I now have is that HWmonitor is registering 4.8Ghz boost clocks once more. Is there any light at the end of the tunnel or should I now admit defeat...?
> 
> ...


Hi,

I updated my BIOS a recently, so I think its the latest version for 7400. Try another reset option in BIOS, if it doesnt work, try the oldest BIOS you could find. Plundervolt was discovered in June, so if you try something around that date or earlier it might work.


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## unclewebb (Dec 31, 2020)

hitsov said:


> Plundervolt was discovered in June


Intel released their first Plundervolt patch December 2019. It has been around for a year now. It took some manufacturers a while before they started adding this fix to their BIOS. 









						INTEL-SA-00289
					

INTEL-SA-00289




					www.intel.com


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