My Laptop's CPU Stuck at Max Turbo 24/7 [Here's Why]

An HP EliteBook 840 G2 with an i5-5300U was stuck at max turbo even while idle, causing overheating and repeated RAPL power-limit hits.

Sysfs and turbostat showed intel_pstate passive mode with the performance governor had pinned both minimum and maximum CPU frequency at 2.9 GHz.

The issue was not a kernel bug, but a tuning/configuration setting that prevented the CPU from downclocking.

A pinned high frequency can waste power, increase heat and noise, shorten battery life, and trigger constant throttling.