CPU suddenly remains hot at idle

[Eamoe]

Hi,

I have a ZBook 15v G5 which has been performing quite well for the past 3 years. I've always turned off the "Fan always on" option in the BIOS. When doing light tasks, the fans very often simply stop. Checking temperatures with HWMonitor, I usually get between 30°C and 40°C on all CPU cores at idle. I'm always very careful with what runs in the background and never let anything hog CPU or memory ressources.

Since this morning, the fans refuse to turn off. Checking temps, CPU cores will suddenly not go below 50°C. Leaving the computer sitting with nothing going on, the fans will spin at stage 1, temps rise to 60°C, fans go to stage 2 for a bit until the cores get to 50°C, fans spin back down to stage 1, and it starts over and over. Where yesterday the computer could sit idle with cores at 30°C indefinitely.

Opening Task Manager and sorting tasks by CPU%, observing idle behavior, the top position is occupied moment to moment by either System, Firefox (writing this post) or rarely Task Manager itself, and percentage never rises above 4.5%.

Doing fairly simple stuff now sees temps shooting to the 100°C region almost immediately. This is insane...

I have not changed anything with respect to software lately. I have opened up the machine to check for dust clogging the convectors or fans blades, but there was nothing as I keep my computer environment usually very clean and smoke-free.

Could it simply be our especially hot 2022 summer making ambient temperature higher? What could cause this? Anyone having a suggestion?

[ub6424]

Hello @Eamoe 

Sorry to hear that you are having problems ... and I would like to help you.

(1) Test your hardware Using the HP PC Hardware Diagnostics (UEFI)

https://support.hp.com/us-en/document/c04499777

See how it works:

https://www.youtube.com/watch?v=14GKIpGPNRM

(2) Please report your results

--- STOP HERE --- Only continue if there are no technical errors.

(3) Update BIOS

HP Notebook System BIOS Update (Intel Processors)

F.33 Rev.A

16.8 MB

May 16, 2022

Download

Why should you install the update ?

https://support.hp.com/us-en/document/ish_4123786-2338478-16

Quote: "

Updating the BIOS is recommended as standard maintenance of the computer. It can also help resolve the following issues:

• An available BIOS update resolves a specific issue or improves computer performance.
• The current BIOS does not support a hardware component or a Windows upgrade.
• HP Support recommends installing a specific BIOS update. 

"

(4) Reboot

(5) Install/Update

HP PC Hardware Diagnostics UEFI

7.6.2.0 Rev.A

42.7 MB

Jun 12, 2020

Download

HP Consumer Desktop / Notebook PC ME Firmware Update

05 Rev.A

30.5 MB

May 14, 2019

Download

HP CoolSense Technology

2.22.2 Rev.A

9.7 MB

Mar 21, 2018

Download

(6) Reboot and test again ...  

(7) Please report your results

[Eamoe]

All of this did absolutely nothing. The computer even has the underside lid removed, exposing all the innards to fresh air... Here attached is the temperatures record after 30 minutes of idle, no internet connection, screen backlight off. Left column is last measurment (takes a sample every 2 seconds or so), middle column is the lowest sensed value, and right column is the maximum value recorded. It has managed to hit 96°C in this condition. Something is deeply wrong and I have no clue what's going on.

[ub6424]

Hello @Eamoe 

! Attention !

With constant overheating, the thermal paste for CPU, GPU and bridges

dries out and loses its function and must therefore be renewed !

If you do not change this condition, notebook/mainboard/components will suffer partial or total damage.

In your case: Service is required !
- The computer should be disassembled and checked.
- Thermal paste for CPU GPU and bridges must be renewed
- The function of the fan(s) must be checked

- Short circuit test ( if required )

- charger/battery test

- Components test

- General cleaning ...

--- HP warranty valid -> Contact HP Support

--- HP warranty expired:

If you can't do that, you should have it <serviced> by a professional notebook (chip level) repair store.

Good luck

[Eamoe]

Thank you very much for your replies. I've done that many times on desktop workstations, never on a laptop. But I should be able to do it.

Best regards

[ub6424]

Hello @Eamoe 

! Please use high quality thermal paste !

The most important document ever !

Download -> Maintenance and Service Guide

( It will help you 100% )

Bottom cover removal:

Page 38 Chapter 5 Removal and replacement procedures for Authorized Service Provider parts

Fans:

Page 51 Component replacement procedures

Heat sink:

Page 53 Component replacement procedures

Please report your results after work is done !

Good luck

[Eamoe]

Okay so, I replaced the thermal paste everywhere where possible, including adhesive thermal pads. Difference is negligible.

But as the days get cooler, I notice things get somewhat better. My hunch is this is due to ambient temperatures. We'll see. It probably was a good thing to do anway.

Pictures for your pleasure:

img_20220806_151543.jpg 

img_20220806_151547.jpg 

img_20220806_151925.jpg 

img_20220806_151933.jpg 

img_20220806_152005.jpg 

img_20220806_152322.jpg 

img_20220806_152650.jpg 

img_20220806_152825.jpg 

img_20220806_154235.jpg 

Thanks again for your help and time.

[ub6424]

Hello @Eamoe 

---

@Eamoe wrote:

...

Thanks again for your help and time.

---

You're welcome !

Great work

Now is the right time to use a cooling pad, see:

https://www.techradar.com/news/best-laptop-cooling-pad

Good luck

[Eamoe]

Okay. Now after a few weeks of use under lower ambient temperatures, I can confirm that this laptop has a serious and impossible to define problem. It continuously idles at 55-60°C with no significant task running and CPU at 1-3%.

It started behaving like this one day without any special action on my part. Planned obsolescence would look exactly like this if I designed it into my product. I'm quite disappointed.

Last resort is a complete Windows reinstall in the hope that it is a software issue, but I can't see how that would be as this unfolds while the CPU is clearly not doing anything.

[ub6424]

Hello @Eamoe 

(1) Set "maximum processor percentage" in Windows to 98%

--->>> How to show or hide Minimum and Maximum Processor State in Power Options in Windows 11/10

(2) Monitor temperatures !

(3) Please report your results