No-Fit in DDR3 Interfaces Due to mem_ck Assignments - No-Fit in DDR3 Interfaces Due to mem_ck Assignments Description This problem affects DDR3 products. A DDR3 memory interface that compiled successfully in version 11.1 of the Quartus II software may encounter a no-fit in version 12.0 if mem_ck is assigned to a differential pin pair where p is inside a DQS group and n is outside the DQS group. Resolution The workaround for this issue is as follows: Open the file xxx_addr_cmd_pads.v in a text editor. Search for the localparam USE_ADDR_CMD_CPS_FOR_MEM_CK and set its value to true . This issue will be fixed in a future version. Custom Fields values: ['novalue'] Troubleshooting novalue True ['novalue'] ['FPGA Dev Tools Quartus II Software'] novalue 12.0 ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']