This answer record discusses the Virtex-7 HT FPGA GTZ Transceiver power-up/power-down sequencing recommendations and their implications.
Recommended Power-up/Power-down Sequence
The recommended GTZ transceiver power-on sequence is VMGTZAVCCL before VMGTZAVCC to achieve minimum current draw. There is no recommended sequencing for VMGTZAVCCH. The recommended power-off sequence is the reverse of the power-on sequence to achieve minimum current draw. If VMGTZAVCC is powered before VMGTZAVCCL, the VMGTZAVCC current draw can increase by 220 mA per transceiver until VMGTZAVCCL is powered up.