Why does my CPU suddenly downclock?

[vismoh2010]

Look at the graph, it suddenly spikes down to like 400 - 500 MHz. I don't want this to happen as it may cause stutters in games. I understand that this might be thermal throttling, but I was under the assumption the CPU gradually downclocks to like 2000 - 3000 MHz when it starts to get hot rather than suddenly going down below the base clock (2.2 GHz).

 

[RJARRRPCGP]

Make sure you got air flow under the laptop!

 

[unclewebb]

Check the Log File box on the main screen of ThrottleStop before you run 3D Mark. When finished testing, exit 3D Mark and then exit ThrottleStop. Attach a log file to your next post. Also attach screenshots of the FIVR and TPL windows and the V/F Point window if you are using that. What laptop model do you have?

Some monitoring software tracks the speed of unused cores so it does not always accurately track the CPU speed. The ThrottleStop log file does an excellent job of tracking any throttling problems.

FYI - Almost all of the popular monitoring software falls on its face when trying to track the CPU speed during a thermal or power limit throttling episode. ThrottleStop uses the Intel recommended monitoring method and does not have this problem.

During Time Spy my 14900HX runs the P cores at a steady 5200 MHz and the E cores at 4100 MHz. The problem with this laptop is the Nvidia 4070 GPU has a low ball power limit for the GPU. Graphics performance is much lower compared to your laptop. CPU performance is much higher.

 

[vismoh2010]

Check the Log File box on the main screen of ThrottleStop before you run 3D Mark. When finished testing, exit 3D Mark and then exit ThrottleStop. Attach a log file to your next post. Also attach screenshots of the FIVR and TPL windows and the V/F Point window if you are using that. What laptop model do you have?

Some monitoring software tracks the speed of unused cores so it does not always accurately track the CPU speed. The ThrottleStop log file does an excellent job of tracking any throttling problems.

FYI - Almost all of the popular monitoring software falls on its face when trying to track the CPU speed during a thermal or power limit throttling episode. ThrottleStop uses the Intel recommended monitoring method and does not have this problem.

During Time Spy my 14900HX runs the P cores at a steady 5200 MHz and the E cores at 4100 MHz. The problem with this laptop is the Nvidia 4070 GPU has a low ball power limit for the GPU. Graphics performance is much lower compared to your laptop. CPU performance is much higher.

View attachment 403757

Rn I'm at school so I'll run 3D Mark again with Log File once I get back home.

If this helps, I've been playing with the power settings on my laptop (Lenovo Legion 7i Gen 9) and I just gave up testing at the end and have all the settings on max rn. With everything on max I have been getting all-time high 3D Mark scores but I am sure that they are not optimal. I also get the occasional computer crash while playing games (Event Viewer Event Code 41: Kernel-Power), but no crashes during 3D Mark for some reason.

 

[unclewebb]

computer crash while playing games

If you are undervolting, an undervolt that is stable in one game or is stable in 3D Mark may not be stable in every game. It is not unusual to have to do some fine tuning until your computer is 100% stable.

 

[SoppingClam]

Look at the graph, it suddenly spikes down to like 400 - 500 MHz. I don't want this to happen as it may cause stutters in games. I understand that this might be thermal throttling, but I was under the assumption the CPU gradually downclocks to like 2000 - 3000 MHz when it starts to get hot rather than suddenly going down below the base clock (2.2 GHz).

Check your 'Power Options' and see if changing from 'balanced' to 'High' or 'Ultimate' fixes that issue. Also, since you are on a laptop, be sure you have it plugged rather than running off the battery when gaming or benchmarking

 

[vismoh2010]

If you are undervolting, an undervolt that is stable in one game or is stable in 3D Mark may not be stable in every game. It is not unusual to have to do some fine tuning until your computer is 100% stable.

I forgot to add the power settings, here they are

 

[vismoh2010]

If you are undervolting, an undervolt that is stable in one game or is stable in 3D Mark may not be stable in every game. It is not unusual to have to do some fine tuning until your computer is 100% stable.

Hi, I have done some testing. It seems I have lost the silicon lottery. I have been undervolting for what seems like forever. Even an undervolt of -75.2 mV causes BSODs. Im really tired so for now I decided to set an undervolt of -50 mV and did a Time Spy run with and without the undervolt.

Here is with the undervolt:

And here is the log file for that run is attached.

And here is when I ran it without the undervolt:

I don't think I will be undervolting anymore since it seems to decrease both CPU and GPU performance for some reason. And without the undervolt, there seems to have been one big spike down in cpu clock. Sadly I forgot to get the log file for this. I will do this and attach that in the next comment.

 

[vismoh2010]

If you are undervolting, an undervolt that is stable in one game or is stable in 3D Mark may not be stable in every game. It is not unusual to have to do some fine tuning until your computer is 100% stable.

I did another run without undervolt and with log files ticked:

This run started at 19:43:10

 

[vismoh2010]

If you are undervolting, an undervolt that is stable in one game or is stable in 3D Mark may not be stable in every game. It is not unusual to have to do some fine tuning until your computer is 100% stable.

here are my throttlestop settings for the undervolt:

I'm really going crazy rn. I don't think Im ever buying a intel processor again considering the amount of shit I'm having to deal with to get some decent performance out of their "best" mobile CPU

 

[unclewebb]

Try setting all of the Turbo Groups to 52. This should allow you to reliably undervolt your 14900HX a lot more. I am at -150 mV for the CPU Core and P Cache with V/F Point 1 set to 150.

Post a TPL screenshot too.

Use ThrottleStop 9.7.3

Your log file shows your laptop has terrible cooling. Your laptop is overheating when power consumption is only 40W or 50W. A 14900HX needs 230W of cooling so it can run at its full rated speed during Cinebench. There is not much hope for a laptop that is poorly engineered with inadequate cooling.

 

[vismoh2010]

Try setting all of the Turbo Groups to 52. This should allow you to reliably undervolt your 14900HX a lot more. I am at -150 mV for the CPU Core and P Cache with V/F Point 1 set to 150.

Post a TPL screenshot too.

Use ThrottleStop 9.7.3

Your log file shows your laptop has terrible cooling. Your laptop is overheating when power consumption is only 40W or 50W. A 14900HX needs 230W of cooling so it can run at its full rated speed during Cinebench. There is not much hope for a laptop that is poorly engineered with inadequate cooling.


View attachment 403811

Would you please tell me why I get lower performance when I undervolt?

And also even when playing fortnite the cpu randomly downclocks to 403 mhz and causes stutters. How do I fix this? Maybe decrease the temp limit?

 

[unclewebb]

why I get lower performance when I undervolt?

Your laptop uses a wide variety of throttling methods. There is thermal throttling, PL1 power limit throttling, EDP current throttling, TVB throttling and worst of all, BD PROCHOT throttling. The last one momentarily slows the CPU down to 400 MHz. This is going to be very noticeable when trying to play a game.

BD PROCHOT throttling is caused by a sensor external to the CPU. Once triggered, it can tell your computer to run at its slowest possible speed. No manufacturer ever publicly documents what sensors can trigger this type of throttling. It might be a sensor within the power adapter or it could be an IR thermometer sensor that measures the temperature of the back side of the keyboard. These severe slow downs seem to happen for about 1.5 seconds on your computer before it resumes running at a reasonable speed.

It is impossible to get consistent performance from a computer when all of these different throttling methods are all occurring randomly. When one throttling method ends, another throttling method begins. Sometimes there are two problems at the same time. Undervolting is not enough to fix a poorly engineered laptop. If you get better results when you do not undervolt then do not undervolt.

The hidden MSI Advanced BIOS allows users to disable and lock out BD PROCHOT to prevent this kind of throttling. I do not believe your computer has a BIOS option to toggle BD PROCHOT off. You would need to modify the BIOS. This is possible in theory but not many people seem to be doing this. I do not remember seeing any guides about this issue. The majority of 12th Gen and newer laptops that I have seen at default settings have all decided to enable BD PROCHOT and then they lock it so you cannot use ThrottleStop to disable BD PROCHOT.

I do not know if your laptop has a completely inadequate heatsink and fan or perhaps someone just did a really bad job installing it. You can try replacing the thermal paste with Honeywell PTM 7950.

You can try using using ThrottleStop to slow your computer down. It does not have adequate cooling so perhaps reducing the P Core turbo groups to about 40 might help the cause. A slower CPU will produce less heat and might help you avoid whatever is triggering BD PROCHOT throttling.

Another trick is to set PROCHOT Offset to 10 or 15. This will start thermal throttling at 90°C or 85°C instead of the full 100°C that your CPU is capable of running at. You will get less peak performance but less heat might be able to help you avoid BD PROCHOT throttling.

If you just bought your laptop then sending it back for a full refund would be a good idea. It is defective by design. All laptops are junk. They all seem to have some severe issues that consumers should not have to waste their time trying to figure out. I managed to get my laptop CPU to run decently but the low ball Nvidia GPU power limit has it limping along like a sick puppy. Fixing the Nvidia GPU throttling problem is on my things to do list.

 

[vismoh2010]

Your laptop uses a wide variety of throttling methods. There is thermal throttling, PL1 power limit throttling, EDP current throttling, TVB throttling and worst of all, BD PROCHOT throttling. The last one momentarily slows the CPU down to 400 MHz. This is going to be very noticeable when trying to play a game.

BD PROCHOT throttling is caused by a sensor external to the CPU. Once triggered, it can tell your computer to run at its slowest possible speed. No manufacturer ever publicly documents what sensors can trigger this type of throttling. It might be a sensor within the power adapter or it could be an IR thermometer sensor that measures the temperature of the back side of the keyboard. These severe slow downs seem to happen for about 1.5 seconds on your computer before it resumes running at a reasonable speed.

It is impossible to get consistent performance from a computer when all of these different throttling methods are all occurring randomly. When one throttling method ends, another throttling method begins. Sometimes there are two problems at the same time. Undervolting is not enough to fix a poorly engineered laptop. If you get better results when you do not undervolt then do not undervolt.

The hidden MSI Advanced BIOS allows users to disable and lock out BD PROCHOT to prevent this kind of throttling. I do not believe your computer has a BIOS option to toggle BD PROCHOT off. You would need to modify the BIOS. This is possible in theory but not many people seem to be doing this. I do not remember seeing any guides about this issue. The majority of 12th Gen and newer laptops that I have seen at default settings have all decided to enable BD PROCHOT and then they lock it so you cannot use ThrottleStop to disable BD PROCHOT.

View attachment 403887

I do not know if your laptop has a completely inadequate heatsink and fan or perhaps someone just did a really bad job installing it. You can try replacing the thermal paste with Honeywell PTM 7950.

You can try using using ThrottleStop to slow your computer down. It does not have adequate cooling so perhaps reducing the P Core turbo groups to about 40 might help the cause. A slower CPU will produce less heat and might help you avoid whatever is triggering BD PROCHOT throttling.

Another trick is to set PROCHOT Offset to 10 or 15. This will start thermal throttling at 90°C or 85°C instead of the full 100°C that your CPU is capable of running at. You will get less peak performance but less heat might be able to help you avoid BD PROCHOT throttling.

If you just bought your laptop then sending it back for a full refund would be a good idea. It is defective by design. All laptops are junk. They all seem to have some severe issues that consumers should not have to waste their time trying to figure out. I managed to get my laptop CPU to run decently but the low ball Nvidia GPU power limit has it limping along like a sick puppy. Fixing the Nvidia GPU throttling problem is on my things to do list.

Thank you so much for your time and dedication to resolve this issue. My laptop is one of the thinner gaming laptops out there at 17.6 mm thickness. Due to this, Lenovo has made quite a few sacrifices on the thermals as you said, and I fully knew this when I bought the laptop.

I have discovered that setting the temperature limit to 97 degrees stops BD Prochot throttling from happening.

Furthermore, I have done some research about undervolting on my particular laptop model and found this reddit post to be useful:

https://www.reddit.com/r/LenovoLegion/comments/1h1pxm1/lenovo_legion_7i_undervolted_stage_1

The OP has managed to get a higher Cinebench score by around +2000 by applying a -110 mV undervolt. Somehow the undervolt he has applied is stable even though he hasn't reduced the turbo group ratios. I suppose I am just unlucky. I will give undervolting one last shot by decreasing the Turbo Group Ratios as you said and trying to run 3D Mark again to see if I get better performance. If I do not, I think it is best to give up on undervolting the CPU.

I would also like to ask if undervolting the E Cache has any noticable difference in performance?

 

[vismoh2010]

Update: Decreasing turbo groups to the values in the Valour549 guide has improved stability. Now I am able to achieve stability at -135 mV. I am yet to do a long OCCT stress test though. This undervolt has helped me to achieve an all time high 3D Mark score for my laptop of 13629!!! I am very pleased. I will post another update after undervolting the E cache too, which I have not gotten to yet

 

[unclewebb]

My laptop is one of the thinner gaming laptops out there

That explains everything. The largest laptops that weigh close to 10 lbs struggle to fully cool a 14900HX when it is running at its full rated speed. I have to go outside during the winter to avoid thermal throttling when running Cinebench on my laptop. Any thin and light laptop with a 14900HX does not have a chance. All you can do is play around with ThrottleStop like you are doing to try and get the best balance between performance and heat.

I am yet to do a long OCCT stress test though

An OCCT stress test is going to be overkill for a thin and light laptop. Finding some voltage settings that are stable in day to day use is more important than if your laptop can survive a melt down stress test.

an all time high 3D Mark score for my laptop

Congrats. It always makes me feel good when I can get a score that is world class compared to other users with the same hardware.

I will post another update after undervolting the E cache too

One person I talked to did not see any significant change when undervolting the E cache setting in ThrottleStop. I have not yet bothered to do any significant testing of this. I reached a point where I was happy with my CPU results so I decided to leave it at that. Finding a way to get the Nvidia GPU up to full power would be a better use of my time.

I am pretty sure that when a 14900HX is loaded, the P cores, the E cores, the P cache and the E cache are all getting fed the exact same voltage from the same voltage rail. Playing around with some of the individual voltages might not accomplish too much. Hopefully you can do some testing and prove me wrong.

 

[vismoh2010]

I am pretty sure that when a 14900HX is loaded, the P cores, the E cores, the P cache and the E cache are all getting fed the exact same voltage from the same voltage rail.

I dont think so. Right now I have my P Core and P Cache at -120 mV, which is stable AFAIK. If I set the E cache to -120 mV, OCCT starts throwing WHEA errors. -115 on the E cache is stable though.

I am concerned because in the Valour549 guide he/she uses a undervolt of -90 mV on the E Cache? Why? Should you not go more than that? He/She is able to go up to -155 mV on the P Core and P Cache, then why stop at -90 mV on the E Cache? I dont think its because of instability issues at higher undervolts because in my case, the E cache is stable at just 5 mV less than the P Cache and P Core.

(Here more means a more negative and less mean a less negative value)

 

[vismoh2010]

That explains everything. The largest laptops that weigh close to 10 lbs struggle to fully cool a 14900HX when it is running at its full rated speed. I have to go outside during the winter to avoid thermal throttling when running Cinebench on my laptop. Any thin and light laptop with a 14900HX does not have a chance. All you can do is play around with ThrottleStop like you are doing to try and get the best balance between performance and heat.


An OCCT stress test is going to be overkill for a thin and light laptop. Finding some voltage settings that are stable in day to day use is more important than if your laptop can survive a melt down stress test.


Congrats. It always makes me feel good when I can get a score that is world class compared to other users with the same hardware.


One person I talked to did not see any significant change when undervolting the E cache setting in ThrottleStop. I have not yet bothered to do any significant testing of this. I reached a point where I was happy with my CPU results so I decided to leave it at that. Finding a way to get the Nvidia GPU up to full power would be a better use of my time.

I am pretty sure that when a 14900HX is loaded, the P cores, the E cores, the P cache and the E cache are all getting fed the exact same voltage from the same voltage rail. Playing around with some of the individual voltages might not accomplish too much. Hopefully you can do some testing and prove me wrong.

Another question,

should the lock button be checked? I saw that it was checked in the Valour549 guide...

Also, Valour549 set the values to 1023 but according to you 0 and 1023 do the same thing, am I right?

 

[unclewebb]

Valour549 guide

The recommended settings in the guide are what worked best for the person that wrote the guide. Do not be afraid to do a few tweaks to those settings. If you can prove that making any adjustment improves the performance or lowers the temperature of your computer then go for it.

-115 on the E cache is stable though

That is interesting. Now the question is, can you prove that setting the E cache to an offset of -115 mV makes any difference to performance or temperatures compared to when the E cache is set to 0 mV? I got tired of testing and tweaking so I just left the E cache at 0 mV. Now that hockey season is finally over, maybe I will have some time to do some more testing or to do some more work on ThrottleStop.

according to you 0 and 1023 do the same thing, am I right?

For the computers that I previously owned, setting Power Limit 4 to 0 or to the max, 1023, did the same thing. When I was testing my 14900HX, setting Power Limit 4 to 0 was causing some EDP throttling. Setting Power Limit 4 to 1023 helped fix the throttling problem that I was having.

I now recommend setting Power Limit 4 to 1023 and I also like to lock this setting to make sure that it does not change.

 

[vismoh2010]

The recommended settings in the guide are what worked best for the person that wrote the guide. Do not be afraid to do a few tweaks to those settings. If you can prove that making any adjustment improves the performance or lowers the temperature of your computer then go for it.


That is interesting. Now the question is, can you prove that setting the E cache to an offset of -115 mV makes any difference to performance or temperatures compared to when the E cache is set to 0 mV? I got tired of testing and tweaking so I just left the E cache at 0 mV. Now that hockey season is finally over, maybe I will have some time to do some more testing or to do some more work on ThrottleStop.


For the computers that I previously owned, setting Power Limit 4 to 0 or to the max, 1023, did the same thing. When I was testing my 14900HX, setting Power Limit 4 to 0 was causing some EDP throttling. Setting Power Limit 4 to 1023 helped fix the throttling problem that I was having.

I now recommend setting Power Limit 4 to 1023 and I also like to lock this setting to make sure that it does not change.

I haven't gotten to testing the performance after the E-Cache undervolt, I will do that today after getting back from school.

The recommended settings in the guide are what worked best for the person that wrote the guide. Do not be afraid to do a few tweaks to those settings. If you can prove that making any adjustment improves the performance or lowers the temperature of your computer then go for it.


That is interesting. Now the question is, can you prove that setting the E cache to an offset of -115 mV makes any difference to performance or temperatures compared to when the E cache is set to 0 mV? I got tired of testing and tweaking so I just left the E cache at 0 mV. Now that hockey season is finally over, maybe I will have some time to do some more testing or to do some more work on ThrottleStop.


For the computers that I previously owned, setting Power Limit 4 to 0 or to the max, 1023, did the same thing. When I was testing my 14900HX, setting Power Limit 4 to 0 was causing some EDP throttling. Setting Power Limit 4 to 1023 helped fix the throttling problem that I was having.

I now recommend setting Power Limit 4 to 1023 and I also like to lock this setting to make sure that it does not change.

Would you please send screenshot of your TPL window? That would help me a lot