Error (176138): Can't place differential I/O pins and/or associated SERDES - Error (176138): Can't place differential I/O pins and/or associated SERDES Description You might encounter this error message in the Intel® Quartus® Prime Software, if you are using Cyclone® IV devices and your output pin uses the LVDS_E_3R I/O standard and is located on a CLKOUT pin. Resolution There is no plan to modify the Intel Quartus Prime Software to fix this problem. You should not assign an output pin with the LVDS_E_3R I/O standard to a CLKOUT pin when using Cyclone® IV devices. Custom Fields values: ['novalue'] Troubleshooting - False ['novalue'] ['FPGA Dev Tools Quartus II Software'] novalue 14.0 ['Cyclone® IV GX FPGA'] ['novalue'] ['novalue'] ['novalue']