The transmitter buffer power(VCCH) of ALT2GXB in basic mode

According to the datasheet of Arria FPGA,the transmitter buffer power of ALT2GXB in basic mode is fixed at 1.5V,but in Quartus 8.0,this option can be either 1.2V or 1.5V,can I choose VCCH to be 1.2V...