CPU Stuck at 0.79 GHz when plugged into ac adapter

[RosePeach]

Hi,

I have a HP Spectre x360 Convertible 13 running Windows 10. When I plug in the wall adapter to charge the notebook the cpu frequency drops to 0.79 GHz. When I unplug the notebook the frequency behaves like normal and turbo boosts around 2.0 GHz.

Things I have tried:

• Fresh install of Windows 10 - same problem
• HP Support assistant to install drivers - same problem
• Ubuntu 19.10 - same problem
• Different power adapter - same problem
• Bios update - same problem
• Bios "power settings" - I have tried both "performance" and "balanced." Neither fix the problem

I have checked the CPU temperature with Aida 64 and the CPU is around 40 degrees Celsius at idle so the CPU isn't thermal throttling.

I have run the HP PC Hardware Diagnostic Windows app and all the "system" & "component" tests passed.

I am at a loss. What can I do to fix this machine? It is out of warranty so that isn't an option.

[The_Fossette]

@RosePeach

Welcome to the HP Support Community!

I reviewed your post and I understand that the CPU speed drop when the charger is connected.

Don’t worry, I assure you I will try my best to get this sorted.

I see that you have already performed all the relevant steps and I recommend you contact support to further diagnose the issue.

Here is how you can get in touch with support.

1)Click on this link – www.hp.com/contacthp/

2)Select the product type.

3)Enter the serial number of your device or select let HP detect your product option.

4)Select the country from the drop-down.

5)You should see the HP phone support number or Chat option listed.

Let me know how it goes and you have a great day!

If you wish to show appreciation for my efforts, mark my post as Accept as Solution. Your feedback counts!

Cheers!

[RosePeach]

Hi,

I have found some more indicators of the problem. In windows 10 I ran the Intel extreme tuning utility. Where it lists TDP, I noticed that while unplugged from AC the highest the TDP will ever go is 5 watts. When plugged in it will never go above 3 watts. Since this issue is present in Ubuntu linux and Windows 10 I believe that there is a bug in the latest BIOS update. Is there any way to install an older BIOS?

[The_Fossette]

@RosePeach,

Follow the steps in the below article to roll back the BIOS to a previous version.

https://support.hp.com/in-en/document/c02693833

If you wish to show appreciation for my efforts, mark my post as Accept as Solution. Your feedback counts!

Cheers!

[gregjohnmason]

Hi Rose - I have the same problem with my Spectre x360 with Kaby Lake 8705G which throttles under minimal power load. Were you able to rollback the BIOS and did it make a difference? I notice that the HP support provided no insight as to whether recent BIOS versions changed any of those settings.

Kind regards,

Greg