FDI or Flexible Display Interface is an interconnect created by Intel in order to allow the communication of the HD Graphics integrated GPU found on supported CPUs with the PCH southbridge where display connectors are attached.
Currently it supports 2 independent 4-bit fixed frequency links/channels/pipes at 2.7 Gbit/s data rate.
FDI enabled processors require FDI enabled southbridge in order to utilize the graphics controller capability, thus boards based on P55,[1] PM55, and P67[2] will not be able to take advantage of the graphics controller present on later processors.
An FDI capable southbridge and CPU pair is not usable without the existence of the appropriate video connectors on the mainboard.
Most of them are also listed on Comparison of Intel graphics processing units, see sections on generations 5, 6, 7, 8.