The Management Engine (ME), part of Intel AMT, is a separate CPU that can run and control a computer even when powered off. The ME has been the bane of the security market since 2008 on all Intel based CPUs, with publicly released exploits against it, is now disabled by default on all Purism Librem laptops.

Source: Purism Librem Laptops Completely Disable Intel’s Management Engine – Purism