First question , Whats motherboard are you using ? Also have you tried alternate outputs , hdmi , display port , dvi . Do you know the monitor works ? Can you test it on a different machine ? Do you have the display set to the right one on the monitor ? Have you double checked everything is properly plugged in including the monitor .So I just bought a 1660ti to upgrade from my rx 480. I replaced the 480 with it and the fans spin, but doesn't display to the monitor. My rx 480 works fine when put back in.
My specs:
i5 6500
8gb ram
500w bronze power supply