Processor Throttle When Plugged In

[VinnieT]

Hi all! I'm helping a friend with their HP 15-dy1031wm. The BIOS is up-to-date as are the BIOS PCDiags. Currently the laptop hangs in the BIOS PCDiags System Extended Test when plugged in and charging, but completes perfectly running on battery. The BIOS PCDiags passes a separate battery and power adapter test. The power adapter is not OEM but we just bought another non OEM power adapter and it does the same thing. I set the fan to always run in the BIOS to help with thermal issues. Any ideas? Thanks in advance!

The original symptoms were a flashing to black screen in a Windows 11 install. A few days after finding a workaround (a cold start was causing the flashing and after a reboot things worked fine) the processor wouldn't go above 16%. I decided to do a clean Windows 10 install. The install ran slow but would get to the OOBE stage. Unfortunately OOBE would loop back to the beginning after completing. All of this was on AC power. I was able to get to the desktop and the previous behavior continued with the CPU throttled to 16% when plugged in and charging.

[erico]

https://support.hp.com/us-en/drivers/hp-15-dy1000-laptop-pc-series/model/34443596?sku=9EM65UA

Did you use the HP Cloud Recovery USB method to reinstall Windows 10?

Invoke the Device Manager and take a look to see if there are missing drivers.

You should be able to get the chipset drivers from the Intel Chipset INF utility.

https://www.intel.com/content/www/us/en/download/19347/chipset-inf-utility.html

In power options you can select what you want the laptop to do on mobile or power connected state.

Selecting Performance will get you more processor power, but less battery use time.

[VinnieT]

Thanks Erico for the quick response! I originally used MS Media Creation Tool to create a thumb drive with Windows 10, but ultimately used the HP Recovery Partition to get back to Windows 10. Both ways produced the same symptoms.

All the power options are set correctly and device manager correctly sees the CPUs. I'm noticing the throttle behavior in the pre Windows environment so it seems beyond a driver issue.

[erico]

How are you determining that there us a power throttle issue pre Windows boot?

Is the BIOS upgraded to the latest version?

Are you sure that this is a power throttle issue rather than a thermal throttling issue?

[VinnieT]

As I wrote, when plugged in the laptop won't complete the BIOS PCDiag System Extended Test. I also notice the cursor movement choppier when plugged in and in the BIOS PCDiag.

Yes, as I wrote the BIOS and PCDiag are up-to-date.

I installed Throttlestop and as soon as I plug in the laptop BD PROCHOT is triggered and the CPU is throttled to .2ghz (2x99mhz). Disabling BD PROCHOT brings the CPU up to about .6ghz. Temperatures though don't go above 40C.

It seems to think it's a thermal issue. I'm going to remove the bottom case and clean.

[VinnieT · Accepted solution]

So I opened the laptop and removed the battery. I then ran the computer on direct power and the throttling still occurred. I put everything back together and reinstalled the OS from the recovery partition ON BATTERY ONLY which gave me no throttling. Once the install completed, I tested with AC power and throttling occurred. I shutdown the computer and upon turning it back on the battery wasn't recognized but CPU still throttled. Upon shutting down again, the laptop wouldn't start even with AC power. I finagled with the power cable and eventually the battery charging light came on so I left the laptop over night.

This morning, everything is running with no throttling, even on AC power. Maybe a complete battery drain helped or maybe resetting the CMOS but I'm thinking it's a hardware failure. Thanks Erico!