Cyclone® IV GX devices are compatible with the 1.4V PCML I/O standard on the receivers.
The only acceptable I/O standard for the transmitters is 1.5V PCML.
The Quartus® II software allows you to select 1.4V PCML on the transmitters up to version 10.1. The actual I/O standard that is implemented is 1.5V PCML, there is no difference in the transceiver configuration when either 1.4V or 1.5V PCML is selected as the I/O standard.
Beginning with the Quartus II software version 10.1 SP1 a fitter error will be generated if 1.4V PCML is selected as the I/O standard for the transmitters. Here is an example of the fitter error:
Error: One or more transceiver atoms cannot be placed
Error: Can't place GXB channel related atom(s)
Error: Can't assign GXB Receiver channel PMA "<component name>" to <location> because this causes failure in the placement of the other atoms in its associated channel
Error: Pin <pin number> does not support I/O standard 1.4-V PCML for <output signal name>
To avoid placement errors, select 1.5V PCML as the I/O standard in your project.