SMBus controller

SMBus is the System Management Bus defined by Intel in 1995. It is used in personal computers and servers for low-speed system management communications. An SMBus controller is integrated into most Intel® chipsets.

The SMBus Controller (or system bus controller) is part of the Intel chipset. It monitors your system board’s temperature and voltage. Programs that read your hardware sensors need the controller.

http://en.wikipedia.org/wiki/Controller_(computing)