Cyclone IV nCONFIG pin is not stable

Hi,

have you also monitored the VCCIO when the nConfig drops, i.e. is the VCCIO not only measured at power up but during Operation as well? Have you also checked that either all physically connected Pins are declared and assigned in QII or - my Option I choose - the "tristate unused Pins" opion is set in QII - Standard is that all unused Pins are driving GND, sometimes this can result in incompatibilities with the board layout in Terms of excessive current consumption, either heating the FPGA or overloading the power supply line..