The only way to be sure it's off is by severing the link between the LM-suffixed Intel Ethernet chip and the PCH. There are two links, the 'normal' one (often M

The only way to be sure it's off is by severing the link between the LM-suffixed Intel Ethernet chip and the PCH. There are two links, the 'normal' one (often MII type, sometimes PCI(e)), and the OOB-one, via SMBus or a comparable I2C style bus between the PCH and the Ethernet chip. Another way that hasn't been verified since in theory the ARC controller could access other PCI devices anyway, is to install a new ethernet card in a free expansion slot and use that instead. AMT is supposedly only supported with a specific CPU, firmware, PCH and PHY combination. Breaking that chain by swapping one of those components with an unsupported one should work. If you simply don't use any of the AMT-enabled interfaces, it shouldn't be able to communicate at all. Best plug in a chopped off ethernet jack to make sure nobody plugs in a cable by mistake. I believe there was a 802.11 variant as well, but that might have been before AMT and around the Centrino era. Best disconnect that as well...