XPS 15 9750 CPU clock speed does not go down

Question

Hi,

I got off the phone after hours of troubleshooting this with Dell support, we agreed to disagree, the guy was saying it is working as designed (because it is a powerful laptop) , I don't think so.

If there are any experts for this topic, please let me know what do you think.

The issue is that the CPU speed sits all the time at 3.9 GHz even if the CPU is only 10-15% utilized. This makes the temperature go to 70-80°C and makes the fans spin which produces some noise. I find this completely unnecessary especially if the computer is just sitting there idle. My wife has a high end laptop from another brand with a CPU of the same generation which works the way how I would expect, but my Dell sits at the maximum for the most of the time (99% of the time or more).

Expected behavior:

- If the CPU utilization is low (<20%), the clock speed is adjusted to lower values (~1GHz)

- If the CPU utilization is high, the clock speed is high

Actual behavior:

- CPU clock speed is around 3.9 GHz at idle times

The model is XPS 15 9570 with i7-8750H CPU

I have installed "Dell Power Manager" and set its "Thermal Management" to "Optimized", I have gone with the Dell support through all the updates they suggested and got my Windows 10 updated at well to the latest patch level.

None of those helped to fix the issue. CPU is still sitting at the max speed, the work-around I do now is to disable Turbo Boost to lower the clock speed to around 2.2GHz which makes the CPU cool and fans silent, but I sacrifice some of the performance which I am not super happy about.

Any insights or suggestions how I could fix this?

durika · Accepted Answer

I have resolved the issue by editing the windows registry, I am not sure which exact option was causing the CPU to get stuck to the maximum clock speed when the AC power was plugged in but I have adjusted all the power relevant power settings for the AC section the same way how they were set in the DC section. It is a shame that neither Microsoft nor Dell provides more transparent power management options while the out of the factory settings are clearly not optimal.

I have exported the section "Processor Power management settings and configurations" and looked at the differences between "AcSettingIndex" and "DcSettingIndex", I have set most of the "AcSettingIndex" the same way they were set for "DcSettingIndex" and now my CPU runs much better.

Not sure if this is on Microsoft or Dell but I feel like I should not be the one doing these changes and just enjoy a product that works perfectly after paying over $3k for it.

Surumee · Answer

I exactly have the same model as yours,Here what i know : 1. Do you know every single things which running on background for your apps or services for the windows ? Do you think even CPU utilization is low there is no hidden proccess running which impact to the performance?are you sure your system is in idle? if you can expand all of that and adjust it to your CPU,you must have your own OS bro,not using windows 10 2. You said if cpu util low, the clock speed will run around 1Ghz, do you even check intel ark for your CPU Spec i7-8750 . Base speed is already 2.2 Ghz, you expected lower than that? 3. What i know is this model is very light, which is it will a little bit sacrifice of your cooling system, you said your wife has high end laptop with the same cpu , which i think it's heavier than this one. Do you realize bigger chasis will optimize a better cooling system ? There are always be pros and cons for every brand and model. 4. If you sacrifice the turbo boost it should be lower your clock speed and get a better cooling system. My result is if you want to get a customize to your cpu, gpu, even your memory, you have a big mistake by purchasing laptop, you should purchase a Desktop. I used this model for almost 1 year,and i am satisfied with the light weight, performance and anything outcome from this model.Based on your post, so far i don't see any issue with your laptop.So better check your expectation again.I hope this can enlighten you.Cheers

durika · Answer

Dear Surumee,

Anyway, I have already fixed the issue by editing the windows registry to adjust the power management to not unnecessarily keep the CPU clock speed so high. However, this should have been done by Dell in the first place to provide a flawless user experience for me as a consumer.

Thanks!

durika · Answer

I was too tired to respond to this in detail yesterday but here we go:

1.
Do you know every single things which running on background for your apps or services for the windows?
- No need for that, task manager gives you a summary
Do you think even CPU utilization is low there is no hidden proccess running which impact to the performance?
- There are no "hidden proccesses", you can see them in task manager, again you can see the summary as well as details in task manager.
are you sure your system is in idle?
- Idle in this context means low CPU utilization.
if you can expand all of that and adjust it to your CPU,
- What?!
you must have your own OS bro,not using windows 10
- I use the stock Windows that came with this laptop

2.
You said if cpu util low, the clock speed will run around 1Ghz
- It should, do you even check intel ark for your CPU Spec i7-8750.
Base speed is already 2.2 Ghz, you expected lower than that?
- Yes, minimum frequency for the processor in question is 800MHz, so it should be running on that frequency if there is no activity.

3. What i know is this model is very light, which is it will a little bit sacrifice of your cooling system, you said your wife has high end laptop with the same cpu
- Not the same CPU, same generation CPU (8th gen), if you read my post properly you would not be writing this nonsense
which i think it's heavier than this one. Do you realize bigger chasis will optimize a better cooling system ? There are always be pros and cons for every brand and model.
- It is smaller and lighter with less cooling but it has proper CPU power management out of the box, unlike DELL. The model is 20q0004vus, if you want to look it up.

4. If you sacrifice the turbo boost it should be lower your clock speed and get a better cooling system.
- I don't want to sacrifice turbo boost, I paid over $3000 for this laptop and expect it run as it should

Now that I addressed all of the unhelpful condescending smug talk, I hope this is the end of our interaction. Be aware that I did not appreciate the tone you used in our call yesterday. I am disappointed by the customer service you demonstrated yesterday, you should work both on your technical and soft skills if you are serious about your career choice.

QuantumMak · Answer

Can you share more about how and what you changed in Windows registry? I have the same issue on my Dell G3 3590. Thank you in advance!

DELL-Chris M · Answer

QuantumMak,

Before making any changes to the registry, back it up.

* Click Windows icon
* Type regedit
* Click regedit
* Click Yes if asked
* Navigate to = Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings
* Highlight PowerSettings
* Right click PowerSettings
* Click Find
* Enter ACSettingIndex
* Click Find Next
* Under DefaultPowerSchemeValues, you will see three folders =

381b4222-f694-41f0-9685-ff5bb260df2e is for the Balanced plan
8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c is for the High performance plan
a1841308-3541-4fab-bc81-f71556f20b4a is for the Power saver plan

* Click the first one
* The right pane should show both ACSettingIndex and DCSettingIndex. What are your current values for both?

* Click the second one
* The right pane should show both ACSettingIndex and DCSettingIndex. What are your current values for both?

* Click the third one
* The right pane should show both ACSettingIndex and DCSettingIndex. What are your current values for both?

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XPS 15 9750 CPU clock speed does not go down

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