As Dortania's Post Install guide says:
... What is AppleSMBus? Well this mainly handles the System Management Bus, which has many functions like:
AppleSMBusController
Aids with correct temperature, fan, voltage, ICH, etc readings
AppleSMBusPCI
Same idea as AppleSMBusController except for low bandwidth PCI devices
Memory Reporting
Aids in proper memory reporting and can aid in getting better kernel panic details if memory related
For install purposes, this SSDT isn't needed but for post-install it's recommended to put the final touches on your hack.
I decided to add it despite not actually needed. God forgive me for being a cbjp.