HP Pavilion (Ryzen 5, Windows 11) CPU drops and locks at 0.4 GHz when unplugged

[Riyaan96]

Hi everyone,

I am using an HP Pavilion laptop running Windows 11, powered by an AMD Ryzen 5 processor. I am experiencing a severe performance issue when disconnecting the charger.

Whenever I unplug the power charger, the CPU speed in Task Manager drastically drops from around 3.5 GHz and gets locked at exactly 0.4 GHz. The entire system becomes incredibly slow. However, the moment I plug the charger back in, the CPU speed immediately returns to normal.

Additionally, I noticed a strange pattern: If I shut down the laptop and turn it on while it is already running on battery power, the CPU speed stays normal (around 3.4 GHz). However, if I plug the charger in and then unplug it even just once, the speed instantly drops to 0.4 GHz and stays stuck there.

What could be causing this issue, and how can I fix it?

[NonSequitur777]

@Riyaan96,

Welcome to our HP Community forum!

The issue you are experiencing is a notorious and well-documented glitch commonly caused by a communication failure between the motherboard firmware (BIOS), the AMD Chipset drivers, and Windows 11 power flags (BD PROCHOT/PROCHOT).

When you unplug the charger, a specific power signal gets "stuck" in a low-power firmware loop. The motherboard incorrectly signals to the operating system that the laptop is either critically overheating or completely out of power, forcing the AMD Ryzen 5 CPU to lock into its absolute lowest emergency power state (0.4 GHz) to prevent hardware damage. Because booting purely on battery completely bypasses the transition phase, the bug does not trigger during a cold battery start.

Fix this software-firmware loop using the following structured troubleshooting steps:

1. Perform an EC (Embedded Controller) Hard Reset

This forces the hardware chip responsible for managing power transitions and battery communication to clear its cached error states.

• Shut down the laptop completely.
• Disconnect the charger and all external USB devices.
• Press and hold the Power Button down for exactly 40 seconds. (The laptop might turn on and back off during this time; keep holding it).
• Plug the charger back in and turn the laptop on normally.

2. Update the BIOS and AMD Chipset Drivers

HP frequently releases firmware updates specifically targeting power-state delivery bugs on Ryzen-powered Pavilion units.

• Open the pre-installed HP Support Assistant app on Windows and run a check for updates.
• Alternatively, go directly to the HP Drivers and Downloads Page, enter your laptop's exact model/serial number, and manually download and install the latest BIOS update and AMD Chipset Driver package.

3. Adjust Windows Advanced Power Settings

Windows 11 may have an artificially low limit configured for its battery profile.

• Open the Start Menu, type Control Panel, and select it.
• Go to Power Options > Change plan settings (next to your active plan) > Change advanced power settings.
• Expand Processor power management.
• Expand Minimum processor state and ensure On battery is set to at least 5% or 10%.
• Expand Maximum processor state and ensure On battery is set to 100%. Click Apply.

4. Toggle the Windows Power Mode Slider

Sometimes forcing Windows 11 to re-evaluate its battery behavior resets the bug.

• Disconnect the charger so the CPU drops to 0.4 GHz.
• Go to Settings > System > Power & battery.
• Locate the Power mode drop-down menu and change it from Balanced to Best Performance. Wait a few seconds to see if Task Manager reacts, then change it back to your preferred setting.

Hardware Note:

If the issue still persists after updating the BIOS and drivers, it points to a faulty internal sensor. Either the charging port/motherboard is failing to read voltage drops correctly, or the internal battery health is possibly degrading. A failing battery may report incorrect power capabilities to the system, causing Windows to lock the CPU at 0.4 GHz to protect itself from a sudden system crash.

Could you let me know if changing the Windows Power Mode changes the speed in real-time, or if you noticed the laptop running unusually hot or loud right before you unplug it?

Kind Regards,

NonSequitur777