The Quartus II software does not perform timing analysis for the FPGA fabric in Cyclone IV GX × variants; consequently, variants that would fail timing analysis are not identified.
This issue affects × variants in the Cyclone IV GX device.
You can manually create the required clock constraint. provides the equation for this constraint. In this equation <n> is 8.000 for a 125 MHz application clock and 16 for a 62.5 MHz application clock.
This issue is fixed in version 10.1 of the Quartus II software.