Due to a limitation of transceiver channel mergining, Quartus® II software cannot fit multiple Triple Speed Ethernet IPs into a transceiver quad unless the gxb_powerdown signal is common to all IPs located within the same quad.
Area: Intellectual Property
Export the gxb_powerdown signal to the top level, and drive the gxb_powerdown signals by a single source. To enable this option in the Triple Speed Ethernet MegaWizard™, enable "Export transceiver powerdown signal" in the PCS/Tranceiver Options tab -> Tranceiver Options. This option is always selected if the multichannel TSE variants are instanced.