Windows CPU Limit Tray

A small Windows tray utility for quickly changing the active power plan's CPU maximum processor state while plugged in.

Useful when a desktop or laptop CPU does not lower clocks properly at idle or light use. Instead of relying on the minimum processor state, this app lets you quickly cap the CPU's maximum allowed state from the tray, then restore it to 100% when needed.

Status

Beta / initial public release.

This app changes a real Windows power setting. Test it on your own machine before relying on it.

Features

• Change the AC / plugged-in CPU maximum processor state
• Preset buttons from 5% to 100%
• Optional small overlay when the CPU limit is below 100%
• System tray menu
• Warning before quitting while below 100%
• Restore 100% and Quit option

What it does not do

• Does not change battery/DC CPU settings
• Does not automatically request administrator permissions (shouldn't require admin)
• Does not directly control BIOS, firmware, undervolting, TDP, or thermal limits

Requirements

• Windows 11 (Windows 10 should work too)
• Python 3.10 or newer recommended
• PySide6

Install

pip install -r requirements.txt

Run

python windows_cpu_limit_tray.pyw

Or double-click windows_cpu_limit_tray.pyw if Python is associated with .pyw files.

Restore CPU to 100%

Use the 100% button in the app, or right-click the tray icon and choose Restore 100% and Quit.

Manual restore command:

powercfg -setacvalueindex SCHEME_CURRENT SUB_PROCESSOR PROCTHROTTLEMAX 100
powercfg -setactive SCHEME_CURRENT

If Windows blocks the change, try closing the app and running it as Administrator. Some managed devices may block power setting changes by policy.

Logs

The app writes windows_cpu_limit_tray.log next to the script when possible, or in the system temporary directory as a fallback.

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