How to fix ACPI.sys High CPU Usage on HP Laptop

The background

When I upgraded my laptop at work to a HP ProBook 440 G5 I faced an annoying issue with the ‘System’ process consuming 15-25% CPU usage constantly. This led to the CPU generating more heat and subsequently causing the fan RPM to increase.

If you search Google for ‘Constant CPU Usage’ you will find numerous ways to identify the culprit process alongside suggestions on how to resolve the issue. I used an application named Process Explorer to identify the culprit.

In my instance, Process Explorer had identified that the ‘ACPI.sys’ thread within ‘System’ was causing the CPU issue. I tried numerous fixes suggested by others such as; changing and restoring power plans and messing around with registry keys which didn’t work.

The fix (at least for me)

HP devices typically come bundled with a lot of bloatware out of the box. The first thing I do is uninstall the bloat and keep only the software that is required to still be able to use all of the hardware such as drivers etc.

I mistakenly left the ‘Intel Rapid Storage Technology’ software installed which, in a nutshell, is designed to increase your hard drive performance based on frequently accessed files being cached.

When I ran the Intel Rapid Storage Technology application I noticed something strange; no hard drives were listed. The penny had dropped, Intel Rapid Storage Technology only detects HDD and SSD through SATA. My new laptop uses an M.2 SSD, therefore the software was redundant. I uninstalled Intel Rapid Storage Technology and rebooted.

Upon rebooting I immediately noticed that the ‘System’ process was no longer consuming CPU usage constantly. It fixed the issue!

The only thing I can think of is that Intel Rapid Storage Technology was looking for a device that didn’t exist and was stuck in a resourceful loop indefinately.

Let me know in the comments below if this helped you.