When the core is generated for the SGMII standard, changes are made to the core that affect the PCS management registers and the auto-negotiation function (see Select Standard). However, the datapath through both transmitter and receiver sections of the core remains unchanged. For the 2.5G mode the GMII interface is over-clocked at 312.5 MHz. 250 Mb/s and 25 Mb/s modes are not supported.