You can set transceiver operating power supply voltages in the Operating Settings and Condition on Assignments/Settings. The Quartus® II software overrides your voltage settings based on transceiver data rate and PowerPlay Power Analyzer (PPPA) estimates transceiver power using overrode voltage settings.
Therefore, PPPA shows the same transceiver power estimation regardless of user voltage settings in some cases.
For example, in a Stratix® V GX device, you can choose VCCR/VCCT from among 0.85V, 0.9V and 1.0V, and VCCA from among 2.5V and 3.0V based on your target device. When the transceiver is configured at a base data rate > 6.5 Gbps, the Quartus II software uses 1.0V for VCCR/VCCT and 3.0V for VCCA regardless of your settings.
Refer to the respective device handbook, datasheet or Pin Connection Guidelines for more details of transceiver power supply voltage settings.